Libya's U.N.-backed unity government said today it taken administrative control of seven ministries in Tripoli including the foreign ministry, as it pushes to extend its control over the capital.

The unity government, whose leaders arrived in Tripoli last month, is designed to replace two rival administrations that were set up in the capital and the east in 2014.

But the new government has moved cautiously as it seeks to secure the backing of numerous armed factions that have exerted control over politics in the capital since the fall of Muammar Gaddafi in 2011.

Speaking at an event to mark the handover of the foreign ministry, Mohamed al-Ammari, a member of the new government's leadership, or Presidential Council, said the transfer of power was "going well".

The other ministries that have been handed over to the Government of National Accord (GNA) were housing and public utilities, transport, social affairs, local government, youth and sports, and Islamic affairs, he told Reuters.

The planning, labour, and education ministries would be handed over in the next few days, he added.

The Presidential Council was forced to arrive in Tripoli by ship after the self-declared National Salvation government, which previously held power in Tripoli, closed down the airspace to prevent them from flying in.

The GNA is has so far failed to obtain a vote of confidence from Libya's eastern-based, internationally-recognised parliament.