Libyan troops have found the bodies of a British man and a New Zealand woman shot dead in western Libya, security officials have said.

The officials said on Thursday that the bodies of the two teachers were found outside an oil gas complex near the town of Zuwarah, 100km west of Tripoli.

"The bodies of a British man and a New Zealand woman who had been killed by bullets were found on the beach in Mellitah on Thursday afternoon," said another source. 

They were found next to their luggage, but their belongings were not stolen and the motive for their killing was unclear.

The teachers' bodies had been moved to Tripoli, where the teachers had worked, a source said. No further details were immediately available.

The gas complex is a joint enterprise of Italy's ENI and Libya's state-owned National Oil Company, which exports natural gas to Italy through the Greenstream pipeline.

A British Foreign Office spokeswoman in London said that diplomats were aware of reports that the bodies of two foreign nationals had been found in Libya.

Americans held

"We are urgently seeking further information from the authorities," she said.

The security situation has deteriorated in recent months in the North African country, where the government is struggling to rein in fighters who helped oust Muammar Gaddafi in 2011 and kept their guns.

A New Zealand Ministry of Foreign Affairs and Trade spokesman said the ministry was aware of the reports.

"We are working with the relevant authorities to confirm this," he said.

In a separate incident, two Americans were being held by the Libyan army at its headquarters in the eastern city of Benghazi, several security and army sources told Reuters news agency.

Both were basketball players and were arrested on the campus of Benghazi University, one security source said.

"They were arrested by university guards and then brought by special forces to the army barracks," an army source said.

The US State Department said it was looking into the matter.

Four American military personnel were detained last Friday by the Libyan government and released after several hours in custody, US and Libyan officials said..

Source: Agencies