A senior United Nations official for Libya has condemned the storming of the parliament’s headquarters by angry demonstrators as part of protests in several cities against the economic turmoil and the political deadlock in the country.

Hundreds of protesters marched in the streets of the capital, Tripoli, and other Libyan cities on Friday, with many attacking and setting fire to government buildings, including the House of Representatives in the eastern city of Tobruk.

"The people’s right to peacefully protest should be respected and protected but riots and acts of vandalism such as the storming of the House of Representatives headquarters late yesterday in Tobruk are totally unacceptable,” Stephanie Williams, the UN special adviser on Libya, posted on Twitter on Saturday.

"It is absolutely vital that calm is maintained, responsible Libyan leadership demonstrated, and restraint exercised by all.”

Friday’s protests came a day after the leaders of the parliament and another legislative chamber based in Tripoli failed to reach an agreement on elections during UN-mediated talks in Geneva. The dispute now centres on the eligibility requirements for candidates, according to the UN.

Libya failed to hold elections in December, following challenges such as legal disputes, controversial presidential hopefuls and the presence of rogue militias and foreign fighters in the country.

The failure to hold the vote was a major blow to international efforts to bring peace to the Mediterranean nation. It has opened a new chapter in its long-running political impasse, with two rival governments now claiming power after tentative steps towards unity in the past year.

Interim Prime Minister Abdulhamid Dbeibah leads a Tripoli-based administration while former Interior Minister Fathi Bashagha draws support from the Tobruk-based House of Representatives and military renegade Khalifa Haftar.