The charges — which were filed by an Ankara court late Friday — come as U.S. 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...
"We were very grateful that Turkish authorities broke up an al-Qaida 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 radical Islamist militants affiliated with al-Qaida are preparing to avenge the May 2 killing of al-Qaida leader Osama bin Laden in Pakistan by U.S. forces.
Al-Qaida's austere and violent interpretation of Islam receives little public backing in Turkey, a predominantly Muslim but officially secular country. However, al-Qaida and several other radical Islamic groups have been active in Turkey before.
The state-run Anatolia news agency reported Saturday that one of the suspects had carried out surveillance around the U.S. Embassy in Ankara and some other foreign missions, including taking photos. Police have seized 1,500 pounds (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-Qaida 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 Muslim militants tied to al-Qaida 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-Qaida-affiliated militants outside the U.S. Consulate in Istanbul left three assailants and three policemen dead.
In 2003, homegrown Islamic militants tied to the al-Qaida attacked the British Consulate, a British bank and two synagogues in Istanbul, killing 58 people.