Kuwaiti police have briefly detained and questioned two men designated by the U.S. Treasury Department as financiers of terrorist groups in Iraq and Syria.

The tiny Gulf emirate has been called the "epicenter" of fundraising for terrorist groups in Syria by a top U.S. Treasury official, and authorities have come under increasing pressure to curtail the flow of funds.

A police officer tells The Associated Press that Shafi al-Ajmi was detained Sunday and Hajaj al-Ajmi was detained late Wednesday, both after returning from abroad. He says the two were detained as a precautionary measure and may be banned from traveling.

He spoke on condition of anonymity because he was not authorized to release the information.

Their lawyer Mohammed Al-Jumia tells the AP his clients only raised charitable donations for Syrians.