Four Egyptian embassy staff have been kidnapped in Libya's capital Tripoli, a day after another Egyptian diplomat was seized by gunmen, the Libyan government has said.

The abductions on Friday and Saturday came days after a powerful Libyan militia reported its leader had been arrested in Cairo and threatened to retaliate.

"Four more have been kidnapped. One of them is the cultural attache and the other three are staff," said a Libyan Foreign Ministry spokesman.

Libya is still in flux two years after Muammar Gaddafi's fall, with the government struggling to control heavily-armed former rebels and militias who fought in the uprising, but often challenge Tripoli's authority.

One militia group, the Operations Room of Libya's Revolutionaries, said on Friday that its leader Shaban Hadia had been arrested in Egypt, where he had been travelling with his family for medical treatment.

Another of the group's leaders, Adel al-Gharyani, denied it had kidnapped the first Egyptian diplomat. But he called on Egyptian authorities to release their commander or there would be a "strong response" from the group.

A number of foreigners have been abducted and attacked in recent weeks. Libyan security forces earlier this week freed a South Korean trade official who had been held for days by kidnappers who authorities 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.

The Egyptian government said on Friday that talks were ongoing to try and secure the release of the first diplomat, an administrative attache.

Source: Agencies