Port Harcourt: Two British nationals were among 14 people arrested on suspicion of attempted bribery in connection with an alleged plot to steal oil from a pipeline, Nigeria said on Friday.

The head of the Joint Task Force (JTF) of military and police in the oil-producing Niger Delta region said the Britons allegedly tried to bribe a senior commander to facilitate the theft.

Oil theft, or “bunkering”, is a major problem in Nigeria, which is Africa’s leading crude producer and exporter.

The practice is said to cost the country some $6 billion in revenue every year, although the government is accused of exaggerating the extent of the problem to cover up embezzlement.

JTF commander General Emmanuel Atewe said the two Britons were detained with 12 technicians they had hired to tap into a Shell pipeline in Warri, the capital of Delta state, and siphon crude onto waiting barges.

“The foreign nationals promised to bribe (a local brigade commander) with 20 million naira ($120,000) and to take care of officers and soldiers along the Chanomi creek,” he told reporters in Yenagoa, the capital of neighbouring Bayelsa state.

“On March 21, 2014, one of the suspects brought $60,000 as part payment for the 20 million naira pledge. The suspects were immediately arrested for attempting to bribe the brigade commander for economic sabotage.”

The suspects, who were paraded before the media in Yenagoa, would be handed over to the Department of State Security for prosecution, he added.

Atewe gave no further details about the pair.

A spokesman for the British High Commission in Abuja told AFP: “We are aware of the two arrested British nationals and we are in contact with the Nigerian authorities concerning their detention.”

On Tuesday, Anglo-Dutch oil giant Shell said it had declared a “force majeure” on crude oil exports from Nigeria as it struggled to repair a sabotaged pipeline at Forcados Terminal in the western Niger Delta.

The under-sea pipeline was shut when a leak was discovered on March 4, leading to the suspension of crude oil exports through the terminal, which can produce up to 400,000 barrels of crude per day.

The closure has raised fears over future supply from Nigeria, which produces more than two million barrels a day.