Bogota, Feb 18 (IANS/EFE) The Colombian navy found and destroyed a semi-submersible vessel with the capacity to carry between eight and 10 tons of cocaine in the province of Narino, but no arrests were made, a senior official said.

The vessel was found in the town of Mosquera, near the Pacific, hidden in dense vegetation, Pacific Joint Command chief Gen. Justo Eliseo Pena told EFE.

The submarine, which was nearly finished, measured 16.9 metres long by 2.75 metres wide.

Authorities are trying to determine who owned the vessel, Pena said, adding that it may have belonged to the Los Rastrojos gang, which operates in the area.

The navy also destroyed a mechanics shop being used to complete the vessel's construction and a camp with the capacity to house about 30 people.

This is the first seizure of a submarine this year.

The custom-built vessels, similar to a submarine, operate with a significant portion of their hulls below the waterline, making it difficult to detect them.

Colombian drug traffickers started using semi-submersibles in 1993. In that year, Colombia's navy seized one of the vessels off Providencia Island in the Caribbean.

The semi-submersibles cannot dive like a normal submarine, but they are equipped with a valve that, when opened by the operators, quickly floods and scuttles the vessel, causing it and any drugs on board to quickly sink to an unrecoverable depth.

The crew then jumps overboard and, since no drugs are discovered, they avoid prosecution.

Since 1993, Colombian security forces have seized 54 of the vessels, with 20 seized last year alone.