UN Secretary General Ban Ki-moon has travelled to Libya's capital to back a reconciliation process urging rival groups to resolve the rift that has left the North African nation deeply split with two separate parliaments and governments.

Mr Ban's visit is his second to Libya since the 2011 fall of long-time dictator Muammar Gaddafi. It comes after the UN launched a dialogue late last month to mediate between the warring Libyan groups.

Libya witnessed a spasm of violence this summer when militias mainly from the western city of Misrata and groups allied to Islamists swept through the capital, backing a government appointed by the country's previous parliament.

Meanwhile, Libya's newly elected parliament and government backed by non-Islamists, driven out of the capital, have been meeting in the country's east.

In a televised session attended by Mr Ban, as well rival politicians and European diplomats, the UN special representative for Libya, Bernardino Leon, said the Libyan capital will be "for the next few hours again the capital of a united Libya."

The meeting was attended by the deputy head of the elected parliament and a representative of the parliamentarians who have boycotted the new House of Representatives.