COLOMBO, Sri Lanka (AP) - Salvage experts failed to tow a fire-stricken container ship carrying chemicals out to sea and it started to sink Wednesday off Sri Lanka's main port, raising fears of a marine environmental disaster, officials said.X-Press Feeders, operators of the container ship MV X-Press Pearl, said the experts were able to board the vessel and attach a tow line, but "efforts to move the ship to deeper waters have failed.""The ship's aft portion is now touching bottom at a depth of 21 meters (70 feet)," while the forward area remains afloat with smoke coming out of two cargo holds, the company said in a statement.Navy spokesperson Indika de Silva said the ship could cause severe pollution if it sinks at its current location off.