TRIPOLI - Five Egyptian diplomats kidnapped in Tripoli in retaliation for Egypt's arrest of a Libyan militia chief pleaded on Saturday for their government to free him to secure their release.

Gunman snatched four diplomatic staff from their homes in the Libyan capital on Saturday, including the cultural attache, and kidnapped another on Friday, forcing Cairo to evacuate its embassy and its Benghazi consulate.

The kidnappings of so many diplomats underlined Libya's persistent chaos two years after Muammar Gaddafi's fall, with heavily-armed former rebels and Islamist militants who fought in the uprising still challenging state authority.

Calling themselves Libyan revolutionaries, the kidnappers contacted Al-Arabiya television channel to demand the release in 24 hours of Libyan militia chief Shaban Hadia, and put one of the Egyptian diplomats on the line.

"The kidnappers have demands and we ask these demands are met and the defendant Abu Hadia be released," a man called Shirbini from the Egyptian cultural center told the channel.

"We won't free the diplomats unless the sheikh is freed within 24 hours," one of the kidnappers said, without giving details of what would happen after that deadline.

Hadia is a commander in the Islamist-leaning Operations Room for Libya Revolutionaries, one of the many militias which fought Gaddafi in the 2011 NATO-backed uprising, but have since refused to disarm and accept Tripoli's authority.

The Operations Room, whose former rebel fighters were nominally hired by the government to secure Tripoli, was accused of briefly abducting Libya's Prime Minister Ali Zeidan in Tripoli in October last year.

The group denied it was involved in the Egyptian diplomatic kidnappings, but on Friday had warned there would be a strong response if Hadia was not released.

"What we have been warning the Egyptian authorities about since yesterday is that this kind of response was to be expected because of the security situation in the country," commander Adel al-Gharyani told Reuters.

Egypt's state news agency MENA said the Egyptian ambassador and numerous diplomats and their families had arrived back in Cairo after the government evacuated the embassy in Tripoli and the consulate in Benghazi as a precaution.

Libyan officials said they were in contact with the kidnappers and an Egyptian foreign ministry spokesman confirmed Hadia was under investigation in Egypt.

"If there is no charge at the end of it then he will be released," he told Al Arabiya. "He will be treated kindly and we expect good treatment of the Egyptians."

MILITIA CHAOS

The Operation Room's commanders operate nominally under the command of Libya's military chief of staff and their commanders rejected any involvement. On Friday they initially warned Egypt of a "strong response" unless Hadia was freed.

The Operations Room is one of the scores of militia groups who battled Gaddafi's forces. But since his fall, rival militias and former rebels have fought turf wars and often used their military muscle to make demands on the government.

Thousands of former fighters are on the government payroll associated with the interior ministry or the defense ministry in an attempt to coax them to join regular armed forces. But many still stay loyal to their brigade commanders.

One former rebel commander who worked for the state-run Petroleum Facilities Guards defected in August and has since seized three key oil ports and held them for months to demand more autonomy from the central government.

When armed gunmen snatched the prime minister from his luxury hotel room in Tripoli in October, the Operations Room first claimed it had arrested Zeidan. They later denied they were involved, when he was released after several hours.

Zeidan, a liberal, had upset Libyan Islamists last year when he visited Egyptian chief of staff General Abdel Fattah al-Sisi after the military deposed Egypt's Islamist president, Mohamed Mursi, following protests against his rule.

Libya's General National Congress is split between the Islamist JCP party, political wing of the Muslim Brotherhood, and the nationalist National Forces Alliance. Some militia brigades are allied to rival political factions.

A number of foreigners have been abducted and attacked in Libya in recent weeks. Security forces in Tripoli earlier this week freed a South Korean trade official held for days by kidnappers who officials said were not politically motivated.

An American teacher was shot dead in Benghazi in December, and in January a British man and a New Zealand woman were killed on a beach in western Libya.