A nuclear-powered US submarine has collided with another US vessel in the Strait of Hormuz, injuring at least 15 sailors, the US navy says.

The incident occurred around 1am local time on Friday when the USS Hartford submarine collided with the USS New Orleans, an amphibious ship, in the narrow strait south of Iran, the navy told Al Jazeera.

Fifteen sailors aboard the Hartford were slightly injured but were able to return to duty, the navy added in a statement.

There were no reports of injuries aboard the New Orleans. But the ship's fuel tank was ruptured in the collision, causing an oil spill of about 95,000 liters of diesel fuel, the statement said.

Evaluating damage

There was no damage to the nuclear propulsion plant of the Hartford, the navy said.

Both ships were heading to port when the incident occurred, Lieutenant Nate Christensen, a navy spokesman, said.

He said the submarine was submerged at the time, but said he could give no further details because the incident is still under investigation.

Authorities are still evaluating the total damage to the vessels, but both ships are currently operating under their own power, the navy said.