The suspects were arrested just days before Turkey hosted the Libya Contact Group meeting in Istanbul [Reuters]

A court has charged 14 suspected al-Qaeda operatives for allegedly planning to attack the US embassy in the Turkish capital.

The court in Ankara formally pressed charges against the suspects late on Friday. Another suspect was released, though may later also face trial.

The suspects were captured just days before the arrival of Hillary Clinton, the US secretary of state, who is in Istanbul for talks with the Libya Contact Group and a meeting on religious tolerance.

The state-run Anatolia news agency said on Saturday that a key suspect had carried out surveillance around the US embassy in Ankara and at some other foreign missions, including taking photos.

It said police have seized 700kg of chemicals along with bomb-making instructions, assault rifles, ammunition and maps of Ankara.

Police captured the suspects after tracking one of them for six months.

One suspect was captured less than a week ago on a street in Sincan, a town on the outskirts of the capital where he is believed to have received weapons training. The others were rounded up on Tuesday.

Attacks in Turkey

Turkish media have speculated that homegrown operatives affiliated with al-Qaeda are preparing to avenge the May 2 killing of al-Qaeda leader Osama bin Laden in Pakistan by US forces.

Al-Qaeda's interpretation of Islam receives little public backing in Turkey, a predominantly Muslim but officially secular country. However, al-Qaeda and other similar groups have been active in Turkey before.

In June, police arrested 10 suspected al-Qaeda operatives in the southern Turkish city of Adana, which is home to the Incirlik Air Base used by the US to transfer noncombat supplies to Iraq and Afghanistan.

Authorities have said fighters tied to al-Qaeda planned to attack Incirlik in the past but were deterred by high security.

Turkish authorities have said dozens of Turks have received training in Afghanistan.

In 2008, an attack blamed on al-Qaeda-affiliated operatives outside the US consulate in Istanbul left three assailants and three policemen dead.

In 2003, homegrown fighters tied to al-Qaeda attacked the British consulate, a British bank and two synagogues in Istanbul, killing 58 people.