YENAGOA, Nigeria (Reuters) - The Nigerian navy has arrested 10 suspects after intercepting a vessel carrying stolen crude oil off the coast of the Niger Delta, a senior military official said on Wednesday.

The suspects - a Nigerian, two Pakistanis, three Ghanaians, one Indonesian, one Beninois and two Ukrainians - had siphoned about two thousand metric tonnes of crude oil from a loading facility belonging to Shell Petroleum, the official said.

“The suspects were caught in the early hours of Tuesday while siphoning crude oil into the vessel from Afremo A platform, a loading jacket belonging to the Shell Petroleum and Development Company in Forcados River,” Navy Commodore Ibrahim Dewu, commander of the NNS Delta, said in a statement.

Nigeria is the world’s eighth biggest exporter of crude oil, but a sizeable proportion of its output is stolen by thieves who either drill into pipelines or hijack barges loaded with oil, theft that is known locally as “bunkering”.

Bunkering and attacks on oil pipelines in the Niger Delta can cut Nigeria’s output, which also affects world oil prices. Militant attacks on production facilities last year slashed output by as much as a third.

Output has started to recover, and the government aims to pump an average of 2.2 million barrels per day this year.