The four include former National Intelligence Organisation (MIT) chief Emre Taner, former deputy under-secretary Afet Gunes and two other MIT members, said Anatolia.

They are to be arrested on sight and hauled to court, according to the warrant issued by the prosecutor.

Taner and Gunes, as well as current intelligence chief Hakan Fidan, were summoned to testify before the court on Thursday about the MIT's secret talks in Oslo with the rebel Kurdistan Workers' Party (PKK) in 2010.

However, the intelligence organisation snubbed the request, telling the prosecutor's office that under MIT rules the prime minister's office must approve any request for cooperation with an investigation, private television station NTV reported.

Top politicians, including President Abdullah Gul, also appeared to back the MIT, suggesting that the officials should be immune from prosecution as they were talking to the PKK on behalf of the state, and with the knowledge of the government.

"MIT has fulfilled its responsibility under the laws," said Defence Minister Ismet Yilmaz in an interview with NTV television.

Prime Minister Recep Tayyip Erdogan has yet to comment on the development despite pressure from the opposition.

Recordings of the Oslo talks between MIT and Kurdish rebels were leaked in the media last year, sparking opposition ire and sending shockwaves through a public accustomed to Ankara's long-standing blanket refusal to talk to the PKK.

Turkish media reported that the MIT officials were summoned by prosecutors because they exceeded their powers by seeking a settlement with the outlawed organisation during the negotiations.

The PKK took up arms in southeastern Turkey in 1984, sparking a conflict that has claimed some 45,000 lives. It is labelled a terrorist outfit by Ankara and much of the international community.