U.S. worried about China protesters

BEIJING, China (CNN) - Eight Americans arrested for planning or staging protests in Beijing on Tuesday and Wednesday remained in Chinese custody Saturday, a U.S. Embassy spokesman said.

"We are continuing to raise our concerns at senior levels of the Chinese government about the eight Americans currently being detained in Beijing," said spokesman J. Alexander Hamilton. "We have asked for their immediate release, and are continuing to follow their cases closely."

Six Americans, members of the group "Free Tibet Reporters." were detained Tuesday on their way to a planned protest, Hamilton said.

Two others were detained Wednesday after hanging a "Free Tibet" banner near an Olympic venue, he said.

"This is the first time that the U.S. Embassy in China is aware of that foreign nationals who were detained for protesting or planning to protest were held for this long," Hamilton said.