The USS Connecticut is a Seawolf-class submarine

Incident on Saturday injured about a dozen sailors aboard the USS Connecticut

A US nuclear submarine was damaged after hitting an unidentified object while operating underwater in Asia, the US Navy said on Thursday.

The USS Connecticut, a nuclear-powered fast-attack submarine, "struck an object while submerged on the afternoon of Oct 2, while operating in international waters in the Indo-Pacific region," the navy said in a statement.

It said there were no life-threatening injuries, but US officials told Reuters that fewer than 15 people suffered minor injuries such as bruises and lacerations. Two of the injuries were categorised as "moderate".

USNI News, a site specialising in navy news, said about a dozen sailors were hurt.

USNI News also reported that the submarine was operating in the South China Sea, where the US Navy has sought to challenge China's disputed territorial claims on small islands, reefs and outcrops.

Officials said it was unclear what hit the submarine. One official said it could have been a sunken vessel, a sunken container or an uncharted object.

The navy said the extent of the damage is being examined and the incident investigated.

"The submarine remains in a safe and stable condition. USS Connecticut's nuclear propulsion plant and spaces were not affected and remain fully operational," it said.

The vessel is now travelling to the US base at Guam.

The incident comes amid rising tensions in the region over China's incursions into Taiwan's air defence zone.