Turkish police have detained 15 suspected al-Qaida militants they said were planning an attack on the U.S. embassy in Ankara and other unidentified foreign targets.

The state-run Anatolia news agency said the suspects were arrested in Ankara and the western cities of Bursa and Yalova in operations on Monday and Tuesday. They said police seized 700 kilograms of chemicals used in bomb making, weapons and ammunition.

The news agency said the police raids came after a six-month surveillance of a key suspect in the case who had received bomb-making training in a foreign country.

Al-Qaida militants carried out a series of bomb attacks in Istanbul in 2003, killing almost 60 people.