Syrian soldiers have killed three Westerners, including an American woman and a British man, both Muslims, in northwest Idlib province near the Turkish border, a monitoring group reported late Thursday.

"They were shot dead during an ambush in the Idlib region and the army found them with maps of military positions," said Rami Abdel Rahman, director of the Syrian Observatory for Human Rights.

The three had apparently been taking photos of military positions on the road between Harim, near the border with Turkey, and the town of Idlib further south when government troops ambushed them, he added.

The incident happened on Wednesday.

The nationality of the third Westerner was not clear, said Rahman.

A U.S. State Department official, in response to a query from AFP in Washington, said "We are aware of the case."

Czech diplomats in Syria were helping them in efforts to get more information.

"Because of privacy considerations, we are unable to comment further," the official added. (AFP)