* Police chief gunned down by unidentified attackers

* Gangs wielding guns, swords, clash in Gaziantep

* Anger over fate of Syrian Kurdish town fuelling unrest

* Airstrikes slow Islamic State advance in Kobani (Releads with Turkish condemnation, adds official reaction, details)

By Humeyra Pamuk and Ayla Jean Yackley

ISTANBUL/MURSITPINAR, Oct 10 (Reuters) - Turkish officials on Friday angrily condemned a wave of unrest in which two police officers were gunned down and Kurds angry over a siege by Islamist militants on their ethnic kin in Syria clashed with security forces and radical Islamists.

Intense fighting raged in the Syrian Kurdish border town of Kobani, where a three-week-old assault by Islamic State fighters has infuriated many of neighbouring Turkey's 15 million Kurds, who want Ankara to intervene militarily.

Automatic gunfire echoed across the border as Islamic State continued their offensive on Kobani, and a Kurdish military official called for a further ramping up of U.S.-led coalition airstrikes, which have slowed the advance of militants into the town.

In Turkey, the fate of Kobani sparked violence this week in more than a third of the country's provinces, leaving 31 people dead, Interior Minister Efkan Ala told a news conference.

"What excuse could possibly justify violence, the death of people and attacks on soldiers and police. Then what's the use of politics," Ala said in the capital Ankara on Friday.

Most of the fatalities were in clashes between rival groups and more than a thousand people had been detained, he added.

The bloodshed risks stirring up deep-running ethnic divisions within Turkey and wrecking a delicately poised peace process aimed at disarming fighters from the outlawed Kurdistan Workers' Party (PKK), who have been fighting a 30-year-old insurgency against the Turkish authorities demanding more autonomy.

A police chief and a policeman were seriously injured and two officers killed on Thursday after unidentified gunmen opened fire with automatic weapons as they inspected shops damaged in earlier unrest in the eastern province of Bingol, according to Dogan News Agency.

Four of the alleged attackers were later killed and two more were caught following a shootout with security forces, the agency reported.

No details of the attackers were available early on Friday and no one claimed responsibility for the reported assassination attempt, the first of its kind since a senior police officer was gunned down in Diyabakir in 2001.

Prime Minister Ahmet Davutoglu told reporters on Friday that "terrorists" had carried out the attack, without giving further details.

GUNS AND SWORDS

The southeastern border province of Gaziantep saw some of the worst violence overnight, when four people were killed and 20 were wounded as armed clashes broke out between protesters demonstrating in solidarity with Kobani and groups opposing them.

Footage showed crowds of mostly men armed with guns, swords and sticks roaming the street of Gaziantep, and two local branches of the Kurdish People's Democratic Party (HDP) in Gaziantep were set on fire, Dogan News Agency reported.

"It is not possible to explain with logic the actions of those who say are worried about a disaster in Kobani trying to drive their own country into a disaster," Huseyin Celik, the ruling AKP's parliamentarian for Gaziantep said, placing the blame squarely on Kurdish groups protesting on behalf of the town.

Police officers were also targeted in attacks in the southeastern province of Siirt, the southern province of Mersin and the eastern Tunceli province, local media reported, whilst government buildings including police headquarters came under attack.

Earlier in the week local media reported that 25 people had been killed after pro-Kobani demontrations erupted into bloodshed during the single deadliest day of civil disorder Turkey has seen for years.

Selahattin Demirtas, the co-chair of HDP, Turkey's leading Kurdish party, on Thursday called for calm and for protests to remain peaceful.

The fledgling Kurdish peace process championed by Turkish President Tayyip Erdogan has helped smooth over some of the bitterness created by the three decade insurgency which left an estimated 40,000 people dead, but recent clashes risk re-opening old wounds.

Kurdish anger over Kobani has also revived long-standing grudges between sympathizers of the Kurdistan Workers' Party (PKK) and Turkey's Hizbullah, a radical Islamist group with strong anti-PKK leanings.

Hizbullah, also a Kurdish group, fought a bloody turf war with the PKK in the 1990s, before renouncing violence a decade ago. Recent tensions led to the group warning last year that it could take up arms once more, however.

The presence of Islamic State on Turkey's borders has also raised fears of trouble amongst a small percentage of radical Muslim Turks who sympathise with the militants.

Another Turkish Islamist group, HUDA-Par, on Friday dismissed suggestions it backed IS, but accused HDP supporters of targeting them.

"Everyone knows very well that HUDA-Par does not support ISIL.... There are no clashes between HDP and Huda-Par. But there are constant and unilateral attacks (against us)."

Speaking on Wednesday, Davutoglu warned against jeopardising efforts to find a lasting peace.

"Where there is no public order, there won't be a peace process, there will be nothing," he said during a speech in Ankara, in reference to the unrest earlier in the week.

KOBANI FIGHTING

The refusal of Turkey - which has NATO's second biggest army - to intervene militarily to halt Islamic State's advance towards Kobani has put it under increasing pressure both from Kurdish groups but also Ankara's western allies.

Turkish officials insist they will not be sucked into unilateral action embroiling them in Syria's bitter civil war, which has already driven more than 1.2 million people across the border, a refugee flood that Turkey has struggled to cope with.

On Friday intense fighting between Islamic State fighters and outgunned Kurdish forces in the streets of Kobani could be heard from across the border.

Jets roared overhead and the western edge of town was hit by an airstrike apparently carried out by U.S.-led coalition warplanes which have intensified their campaign against IS targets around Kobani in recent days.

The militants controlled swathes of the eastern parts of town and smaller areas in the south, according to the UK based Syrian Observatory for Human Rights, who said IS was trying to seize the road leading into Turkey, thus cutting off the Kurdish defenders entirely.

"They are trying to advance on the crossing from the east ... but the YPG (fighters) are resisting them," Ocalan Iso, the deputy head of the Kurdish forces defending Kobani, told Reuters.

IS fighters had been forced to abandon larger vehicles and take to motorbikes to avoid U.S. coalition airstrikes, Iso said.

"The (aerial) bombardment is going well, but we ask for more," he added, speaking by telephone from Kobani.

The Islamists have been gradually tightening their stranglehold on Kobani for more than three weeks, using heavy artillery to pound residential areas and sending an estimtated 200,000 people, mostly Syrian Kurds, fleeing across the border.

Kurdish officials have called for Ankara to allow weapons and fighters to flow into Kobani from Turkey, but Turkish officials are reluctant to help the town's defenders, because they have strong links with the PKK, still viewed as a terrorist organisation in Turkey, the U.S. and Europe. (Reporting by Seda Sezer in Istanbul, Oliver Holmes and Tom Perry in Beirut, writing by Jonny Hogg, editing by Philippa Fletcher)