Italian police said the hijackers had given themselves up after a short period of negotiations.

Turkish television initially quoted police sources as saying the plane had been hijacked in protest at a planned visit to Turkey next month by the Pope, who offended many Muslims with a speech last month linking the spread of the Islamic faith to violence.

But Turkish television later reported one of the hijackers had converted to Christianity and was a conscientious objector.

It said he had sent a letter to the Pope in late August, asking for his help to avoid compulsory military service in Turkey. It quoted the letter as reading: "I am a Christian and I do not want to serve in a Muslim army."

The Vatican said the Pope was being kept informed about the hijacking but preparations for the trip were still going ahead.

Police, military and fire brigade vehicles surrounded the Turkish Airlines plane at Brindisi airport in southern Italy, where the aircraft, carrying 107 passengers and six crew, landed after being escorted down by Italian jets.

"They have surrendered and are about to get off the plane," Brindisi Police Chief Salvatore De Paolis told Reuters. "They will request political asylum." The Italian news agency ANSA said later that both hijackers had been detained by police.

Aviation authorities said passengers had begun to leave the plane but local news reports said only one crew member, a co-pilot, had got off and the passengers were still on board.

A spokeswoman for Italy's civil aviation authority ENAC told Reuters earlier: "As far as we know, the hijackers want to talk with Italian authorities to send a message to the Pope."

Turkish Airlines told Turkish NTV television pilot Mursel Gokalp had said the passengers were all well and the hijackers were not armed. CNN Turk's Web site said that, of the 107 passengers, 80 were Albanian and five Turkish.

Police with dogs patrolled the airport, which was immediately closed and crowded with stranded passengers.

"The two hijackers want to speak to journalists so they can send a message to the Pope and explain why they did this," a fire rescue squad official at the airport told Reuters.

Vatican spokesman Father Federico Lombardi said the Holy See was following developments closely and that preparations for the November 28-December 1 trip to Turkey were going ahead.

The Pope has said he regrets the offence caused by his speech, in which he used a medieval quotation linking the spread of the Islamic faith to violence, and said he was misunderstood. But Turkish Prime Minister Tayyip Erdogan has been one of those who have said they are not entirely satisfied with the apology.

Private broadcaster CNN Turk reported that Italian officials had refused the hijackers' request to contact the Pope.

A Greek Defense Ministry official said the plane had entered Greek air space at 5:58 pm (1458 GMT) and was escorted out by the Greek fighter jets. The Italian air force later said it had intercepted the flight, which then landed at Brindisi.

Benedict is due to visit Ankara, Istanbul and the ancient site of Ephesus as a guest of Turkish President Ahmet Necdet Sezer from November 28 to December 1.

A number of planes have been hijacked to or from Turkey in the past decade, either by Kurdish rebels or hijackers with Chechen or Islamist sympathies. Reuters