"If the allegations are true, it means that a planned murder is being consciously committed," Aysel Tugluk, deputy chairwoman of the Democratic Society Party (DTP), told reporters here.

"Ocalan wields influence over the Kurdish people," she said. "If something bad happens, those who sympathise with him will react... Turkey will be faced with very serious dangers."

Tugluk argued that "some people may be planning a Turkish-Kurdish (civil) war" and urged Ankara to allow an independent medical commission to examine Ocalan's health and the poisoning claims, made by Ocalan's lawyers at a press conference in Rome Thursday.

The lawyers said laboratory tests on hair samples from Ocalan, 58, indicated the presence of what they described as toxic metals, including levels of chromium seven times higher than normal and high levels of strontium.

Ocalan, who led a bloody separatist rebellion in southeast Turkey from 1984 until his capture in 1999, is experiencing breathing and skin problems as well as severe pain which is interrupting his sleep, they said.

The justice ministry ordered an investigation into the allegations, even though it played them down as an attempt to revive international interest in Ocalan.

In February last year, Italian lawyers of the rebel chieftain said he was in serious condition after suffering a heart attack. Turkey denied the claim.

Ocalan is the sole inmate on the prison island of Imrali in northwestern Turkey, where he is serving a life sentence for treason and separatism.

Council of Europe officials, who have several times visited Ocalan, have found his jail conditions satisfactory, but have urged Ankara to ease his isolation.

Ocalan's Kurdistan Workers' Party (PKK) is listed as a terrorist group by Ankara and much of the international community, but to many among Turkey's sizeable Kurdish minority its militants are freedom fighters.

The PKK campaign for Kurdish self-rule in the southeast has resulted in more than 37,000 deaths.