The United States is "keeping watch" on the situation of some 15 British sailors being held by Iran, White House spokesman Tony Snow said on Friday.

"They (sailors) were engaged in routine boarding operations of merchant shipping in Iraqi territorial waters," said Snow. "We're keeping watch on the situation."

The British sailors "were moved into Iranian waters," Snow said. "At this point, what we're doing is staying in touch with the British," he added.

Iran's detention of British sailors occurs at the time when Iran is facing increasing international pressure due to its nuclear program. Britain has been a staunch ally of the U.S., which is calling strongly for sanctions against Iran.

It was reported that Britain, which is seeking urgent clarification from Tehran over the incident, has demanded the immediate release of the British sailors after they were seized by Iranian naval vessels in the Persian Gulf on Friday.

Source: Xinhua