The charges — which were filed by an Ankara court late Friday — come as US Secretary of State Hillary Rodham Clinton visits Turkey’s cultural capital of Istanbul for a meeting on religious tolerance.

The 14 suspects were captured just before Clinton’s arrival. A 15th suspect was released, though may later also face trial.

“We were very grateful that Turkish authorities broke up an Al-Qaeda plot that was aimed at American targets in Ankara just a few days ago,” Clinton said in Istanbul on Saturday.

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

The state-run Anatolia news agency reported Saturday that one of the suspects had carried out surveillance around the US Embassy in Ankara and some other foreign missions, including taking photos. Police have seized 700 kilograms of chemicals along with bomb-making instructions, assault rifles, ammunition and maps of Ankara, it said.

Police captured the suspects after tracking one of them for six months, according to Anatolia. The police captured him 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.

In June, police arrested 10 suspected Al-Qaeda militants in the southern Turkish city of Adana, which is home to the Incirlik Air Base used by the United States to transfer noncombat supplies to Iraq and Afghanistan. Authorities have said militants tied to Al-Qaeda planned to attack Incirlik in the past but were deterred by high security.

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

In 2008, an attack blamed on Al-Qaeda-affiliated militants outside the US Consulate in Istanbul left three assailants and three policemen dead.

In 2003, homegrown militants tied to the Al-Qaeda attacked the British Consulate, a British bank and two synagogues in Istanbul, killing 58 people.