TRIPOLI (Reuters) - A self-declared prime minister sidelined by Libya’s U.N.-backed government tried to seize the defense ministry and other state offices on Thursday, but a government spokesman said the attempt to capture the buildings by force had failed.

The claims and counter-claims could not be independently confirmed, but the incident showed the extreme frailty of the U.N.-backed Government of National Accord (GNA), which has only ever had partial control over Tripoli since its leaders arrived in the city last March.

It comes after the capital has suffered crippling power and water cuts during unusually cold winter weather, compounding the suffering of residents already struggling with a liquidity crisis and a breakdown in public services.

Khalifa Ghwell, head of the self-declared government that ran Tripoli until early last year, said in a televised speech that his forces had recaptured some “state institutions” including the ministry of defense, and that he had ordered staff there back to work. A statement by supporters of Ghwell said the labour and martyrs’ ministries were also under their control.

A statement on a GNA Facebook page said that “at a time when the (GNA) is working for agreement between the parties and a solution to everyday problems, armed groups loyal to ... Ghwell tried to storm a number of state headquarters in the capital, Tripoli”. The groups used the “threat of force” on entering the labour ministry, a second statement said.

“POLITICAL FARCE”

A GNA spokesman said late on Thursday that the move had foundered. “Business in Tripoli is back to usual. There was an attempt to occupy some government buildings but all maneuvers failed,” the spokesman, Ashraf al-Tulti, told Reuters.

Tripoli is home to a patchwork of armed groups with shifting loyalties. Some have sided with the U.N.-backed Government of National Accord (GNA), some support Ghwell, and some do not have clear political allegiances.

In October, armed groups backing Ghwell took control of a complex used by a parliament aligned with the GNA, and Ghwell has made several public appearances in which he has challenged the GNA’s authority.

Ghwell, who has opposed the GNA from the start, said on Thursday the government and the U.N.-mediated agreement that created it had failed. “What is a shame is the continuation of this political farce, as well as the tampering with security and the economy, and the level of humiliation, indignity and poverty this agreement has brought on citizens,” he said.

Western powers backed the GNA in a bid to end the political chaos that developed in Libya after the uprising that toppled Muammar Gaddafi in 2011. It was meant to unify rival governments set up in Tripoli and eastern Libya in 2014, as well as the armed factions that back them.

But the GNA has struggled to impose its authority in the capital, remaining half-formed and short of popular and logistical support. It has also failed to win endorsement from power-brokers in the east.

Brigades of former rebels have often stormed government offices, ministries and the parliament in Libya over the last five years to make political demands or call for higher salaries. Armed groups have used their power to give their members and allies ministry jobs.