MANAMA (AFP) - A nuclear-powered US submarine and an amphibious vessel collided in the strategic Strait of Hormuz on Friday slightly injuring 15 sailors and creating a fuel spill, the US Navy said. "The collision between USS Hartford (SSN 768) and USS New Orleans (LPD 18) occurred at approximately 1:00 am local time (2030 GMT on Thursday)," the Bahrain-based Fifth Fleet said. "Fifteen sailors aboard the Hartford were slightly injured and returned to duty. No personnel aboard New Orleans were injured," it added. The New Orleans' fuel tank ruptured, causing a 25,000 gallon (95,000 litre) spill of diesel fuel but the propulsion plant of the submarine was unaffected, a statement said. Both ships are operating under their own power and the overall damage to both vessels is being evaluated, the statement added. Navy spokesman Lt Nathan Christensen told AFP "we are trying to evaluate the spill and find out whether it has dissipated." He added that the incident "has not affected the shipping" running through the strait. The Strait of Hormuz, less than 100km at its widest point, separates Oman from Iran and is the gateway into the oil-rich Gulf. An estimated 40pc of the world's crude oil passes through the strait on the way to market. Both the submarine and the ship are on regularly scheduled deployments to the US Navy Central Command area of responsibility, the navy said. The Hartford has a history of bad luck. In 2003, it ran aground while on manoeuvres in the harbour of La Maddalena, Sardinia. It was out of commission for months as millions of dollars of damages were repaired. The Los Angeles class nuclear-powered vessel is a fast attack submarine, with a displacement of approximately 6,900 tonnes, according to the US Navy website. With a crew of 13 officers and 121 enlisted men, it is based in Groton, Connecticut. The 110-metre-long Hartford is armed with Tomahawk cruise missiles and MK48 torpedoes. The diesel-powered New Orleans is a San Diego class amphibious transport dock with a displacement of around 24,900 tons and a crew of 28 officers and 333 enlisted men. The 206-metre-long vessel is armed with Bushmaster II 30mm guns and rolling airframe missile launchers.