HONG KONG, July 28 (Reuters) - A U.S. aircraft carrier and its strike group have returned to the South China Sea after a port call in Singapore, deploying in the disputed region as tensions with China rise over a possible visit to Taiwan by congressional leader Nancy Pelosi.

Officials with the U.S. Navy's Seventh Fleet confirmed the deployment of the USS Ronald Reagan to the vital trade route but did not comment on questions about tensions over the trip by Pelosi, speaker of the U.S. House of Representatives.