Turkish police have arrested 16 people on suspicion of planning to bomb next month's Nato summit in Istanbul.
Police seized various items in the raids last Thursday
The suspects - held in Bursa - were members of the radical Islamic group Ansar al-Islam, believed to have links to al-Qaeda, police said.
Guns, explosives, bomb-making booklets and 4,000 CDs with training advice from Osama Bin Laden were also seized.
US President George W Bush and other world leaders are due at the summit being held on 27 and 28 June.
Sixteen of the suspected militants were arrested in Bursa, a city about 250km (160 miles) south of Istanbul. Nine were held in Istanbul as well, but were later freed by the state security court.
"The organisation has been neutralised in a successful operation while in the stage of planning attacks," Bursa governor Oguz Kagan Koksal was quoted as saying by Turkey's Anatolia news agency.
With up to 50 world leaders scheduled to attend, Turkey is under pressure to ensure security is water-tight for the Nato summit.
Fears of attacks have been heightened since the four suicide bombings in Istanbul last November.
Sixty-two people were killed and hundreds injured when two synagogues, the British consulate and HSBC bank were targeted in Turkey's largest city.