An Istanbul prosecutor filed the charges against Irfan Dundar and Mahmut Sakar for claiming earlier this year that PKK leader Ocalan is being progressively poisoned in prison, Anatolia news agency reported.

Dundar and Sakar were among Turkish and Italian lawyers who made the claim at a press conference in Rome in March, citing test results indicating what they described as toxic metals, including high levels of chromium and strontium.

The charge sheet said the two lawyers' allegations had served as an order to PKK sympathisers in Turkey and abroad to carry out protests and spread the organisation's propaganda, Anatolia said.

It asked for up to 15 years imprisonment for both on grounds that they are PKK members.

An arrest warrant was issued against Sakar, who used to serve in a senior position in a now-banned Kurdish party, Anatolia said.

Turkey has denied the poisoning claims, saying toxicology tests conducted on the jailed leader were negative.

Ocalan, 58, has been serving a life sentence for treason and separatism as the sole inmate on a prison island in the Marmara Sea since his capture and conviction in 1999.

More than 37,000 people have been killed since 1984 when the PKK took up arms for self-rule in Turkey's mainly Kurdish east and southeast.

The PKK is listed as a terrorist organisation by Turkey, the European Union and the United States, but sympathisers among Turkey's large Kurdish community consider its members freedom fighters.