ISTANBUL, Turkey — The Kurdistan Workers Party (PKK) militant group declared a "formal and clear ceasefire" with Turkey on Saturday after the rebels' jailed leader ordered an end to the decades-long armed campaign for autonomy.

"Since March 21 and from now on, we as a movement, as the PKK ... officially and clearly declare a ceasefire," Murat Karayilan, the PKK's field commander, said in a video address posted on Firat News, a Website with links to the militants.

Abdullah Ocalan, held in an island prison since his 1999 conviction for treason, called on the PKK on March 21, the Kurds' traditional new year holiday, to ceasefire and withdraw from Turkey.

Ocalan has been in negotiations with state officials since October to end the conflict that has claimed 40,000 lives since it began in 1984.

Karayilan's declaration, made to a crowd of Kurds gathered in Bonn, Germany, to celebrate the new year, had been expected but was still an important sign that the outlawed PKK will abide by Ocalan's orders. Ocalan still wields enormous clout over PKK militants as well as millions of nationalist Kurds.

Karayilan is based in the remote mountains of northern Iraq from he directs the PKK insurgency against Turkey. The United States and the European Union, along with NATO member Turkey, consider the PKK a terrorist organization.