(Updates with clashes)
TRIPOLI, Jan 21 (Reuters) - Libya's Islamist Justice and Construction Party said on Tuesday its five ministers, including the oil minister, would resign from the government, complicating Prime Minister Ali Zeidan's efforts to stabilize the OPEC nation.
Two years after Muammar Gaddafi's fall, the oil-producing North African state has struggled to overcome political turmoil and the challenge of heavily-armed ex-rebels and militants who fought in the 2011 revolt against the autocrat but now refuse to disarm.
At least two people were killed in clashes on Tuesday west of Tripoli when soldiers and militia allies attacked an area where they said gunmen loyal to Gaddafi were holed up, a Reuters witness and officials said.
Resignations by JCP, which repeatedly failed to secure a vote of no-confidence against Zeidan, will deepen deadlock in the General National Congress (GNC) parliament, which has made little progress in Libya's transition to democracy.
"Zeidan failed in his duty to provide security, and to deliver in the electricity and oil sectors," Nizar Kawan, a leading JCP member, said in a statement. "We had asked for a withdrawal of confidence, but some don't understand the danger of the stage we are at now."
The GNC is caught in a stalemate between the JCP, the political wing of the Muslim Brotherhood, and the leading parliamentary party, National Forces Alliance, a more nationalist coalition.
Since the GNC was elected more than a year ago, infighting has delayed legislation, and Libya still has no constitution.
Tuesday's clashes broke out after soldiers backed by militia fighters loosely aligned with the government stormed the Warshafena area on the western outskirts of Tripoli to capture gunmen they accused of belonging to pro-Gaddafi forces.
At least two people were killed when troops and militiamen fired anti-aircraft guns and rockets into the area where they had said tribal fighters resisted with rockets, a Reuters witness and hospital officials said.
The fighting was the heaviest since rival former rebels and militiamen withdrew from their bases in the Libyan capital late last year when street clashes killed dozens of protesters demanding militias pull out of the city.
Controlling former fighters and tribal demands is a major challenge for the fragile central government. One former rebel commander has seized eastern oil ports since August, choking off oil shipments to demand more autonomy. (Reporting by Ghaith Shennib, Feras Bosalum and Ayman Salha; writing by Patrick Markey; Editing by Janet Lawrence)