Libya 'releases' four US military personnel

Libyan authorities have detained four American military personnel, the US government has confirmed.

'We are seeking to ascertain the facts and ensure their release,' US State Department spokeswoman Jen Psaki said.

The US citizens were reportedly arrested near the city of Sabratha, west of the Libyan capital, Tripoli.

Images purporting to show two of the Americans' passports and embassy ID cards have been posted on social media websites.

The head of Sabratha's military council said the US military staff were travelling in two SUVs when they were stopped at a checkpoint.

The Americans were allegedly armed and carried communications equipment.

One of their cars was said to have been set on fire afterwards.

US diplomats have operated in the country under very tight security since last year's attack on the US consulate in the city of Benghazi, in which US ambassador Christopher Stevens and three other Americans were killed.

The security situation in and around Benghazi has been worsening in recent months, with militants blamed for almost daily attacks.

Last week, seven people were killed at a security checkpoint near Benghazi in the first known suicide bomb attack in Libya since the fall of Col Gaddafi two years ago.