Two British journalists have been arrested in Libya, the Foreign Office has confirmed.

Nicholas Davies, a reporter, and cameraman Gareth Montgomery-Johnson, who work for Iranian-owned Press TV are being held in custody in Tripoli alongside two local men, the news network said on its website.

The reporters and the two other men, identified only as Muhammed and Assad, were detained by members of the Misrata Brigade, and efforts are under way to secure their release, the English-language organisation added.

A Foreign Office spokeswoman said: "We can confirm that two British nationals have been detained. The embassy in Tripoli is providing consular assistance."

She added that the arrests took place on Wednesday.

Montgomery-Johnson's sister Melanie Gribble told the South Wales Evening Post that her family is anxiously waiting for information, having only been alerted to the arrest yesterday morning by a friend who had seen the Press TV website.

She said: "I am asking the Government to please do everything they can and keep us informed."

The 37-year-old, from Carmarthen, west Wales, has been covering the Libyan conflict for Press TV since last summer, his sister added. He started working for the TV station last year, having studied broadcast journalism in Falmouth, Cornwall.