Around 20 demonstrators barged past UN security guards and into the main courtyard of the Palais des Nations before being ejected.

"Ocalan's been poisoned, that's why we're here," one demonstrator, who gave his name as Erdam, told AFP.

Kurds from all over Switzerland had gathered in protest, he added.

Ocalan is the head of the Kurdistan Workers' Party (PKK), which has been fighting an armed separatist campaign against Ankara since 1984. He has been in jail in Turkey since 1999.

His lawyers in Rome on Thursday claimed he has been poisoned in jail, and demanded the UN send a medical team to investigate.

Ocalan's defence team showed reporters in the Italian capital the results of tests indicating the presence of what they said were toxic metals in the Kurdish leader's hair.

Italian lawyer Giuliano Pisapia said Ocalan was suffering a "progressive poisoning" and ruled out the possibility that the metals had entered his body naturally.

"There are only two other possibilities -- poisoning through his food or through his water," he told a press conference.

Lawyer Mahmut Sakar called on the United Nations and the Council of Europe to send an "independent medical delegation" to examine the PKK chief.