ISTANBUL (AP) — Turkish police have arrested 15 people for alleged links to the extremist Islamic State group, the country's official news agency said late Saturday, following days of security warnings by Western consulates.

Anadolu news agency, sourcing an Istanbul police statement, said the group was detained for purportedly planning attacks on the Swedish and Dutch Consulates in Istanbul as well as on churches and synagogues. But the police added they couldn't ascertain any “concrete threats” against the locations.

The intelligence that led to the police operation stated that the group may have received instructions from an affiliate of IS called Islamic State-Khorasan Province, which is active in South Asia and Central Asia.

Sweden and the Netherlands have been the subject of angry protests in Turkey after an anti-Muslim activist burned the Muslim holy book in Stockholm. and a similar action took place in The Hague.

This week, a group of Western countries temporarily closed down their consulates in Istanbul over security concerns. Turkish government officials accused them of failing to share information on the security threat that led to the closures and of aiming to cause harm to Turkey.

In November, a bombing on Istanbul’s bustling Istiklal Avenue, located in the heart of the city and near a number of foreign consulates, killed six people and wounded several others. Turkish authorities blamed the attack on Kurdish militants but they have denied involvement.