Turkish Prime Minister Tayyip Erdogan has ruled out a general amnesty for Kurdish militants but said intelligence agents would continue talking to the rebels' jailed leader in a bid to end a near three-decade insurgency.

Mr Erdogan's chief adviser said last week that Turkish officials had been discussing disarmament with the Kurdistan Workers Party (PKK) and on Thursday two Kurdish lawmakers paid a rare visit to the militant group's leader in his island prison.

Although Turkish authorities have held talks in the past with the PKK, the negotiations were secretive and largely appeared to have run aground.

Mr Erdogan said Turkey was taking a two-pronged approach, with the state intelligence agency talking to PKK leader Abdullah Ocalan, imprisoned on the island of Imrali since his capture in 1999, and the government talking to Kurdish politicians.

"Talks with Ocalan is not a new process ... I have said before that we will negotiate with (Kurdish) politicians and struggle against terrorism," Mr Erdogan said before leaving for an official visit to West Africa.

He ruled out an amnesty for PKK fighters or the possibility of Mr Ocalan being released from Imrali and placed under house arrest.

Better conditions for Mr Ocalan are one of his supporters' demands.