* Self-declared Libyan National Army takes on Islamists
* Parliament chief accuses general of staging a coup
* At least 75 killed in fighting; Benghazi airport closed (Updates death toll)
By Ayman al-Warfalli and Ulf Laessing
ABYAR/TRIPOLI, Libya, May 17 (Reuters) - The self-declared Libyan National Army led by a renegade general told civilians on Saturday to leave parts of Benghazi before it launched a fresh attack on Islamist militants, a day after dozens were killed in the worst clashes in the city for months.
Families could be seen packing up and driving away from western districts of the port city where Islamist militants and LNA forces led by retired General Khalifa Haftar fought for hours on Friday.
Dressed in military uniform, Hafter - whom the speaker of parliament accused of plotting a coup - said his troops had temporarily withdrawn from Benghazi for tactical reasons.
"We'll come back with force," he told reporters at a sports club in Abyar, a small town to the east of Benghazi.
"We've started this battle and will continue it until we have reached our goals," he said.
He said government and parliament had no legitimacy as they had failed to achieve security. "The street and the Libyan people are with us," he said, adding that his troops were spread out in several parts of eastern Libya.
In Tripoli, parliamentary speaker and military commander-in-chief Nuri Abu Sahmain said Hafter was trying to stage a coup.
"(LNA) members who have carried out the clashes in Benghazi are out of the control of the state of Libya and they are trying to attempt a coup for their own interests," Abu Sahmain said in a televised news conference.
A Health Ministry official said the death toll had risen to 43, with more than 100 wounded. Haftar said 60 militants and six of his soldiers were killed, and 250 militants and 37 of his men wounded.
Libyan news website Ajwa Belad said late on Saturday 75 people had been killed and 141 wounded, citing official data.
A worker in a hospital that received at least 40 corpses said: "More bodies are coming in from areas outside Benghazi."
Authorities extended the closure of Benghazi's Benina airport on Saturday. Egyptair halted flights to Benghazi until the security situation improved, an Egyptian security official said.
The Libyan army declared a no-fly zone after Haftar's forces used at least one helicopter during Friday's fighting, according to a statement on the chief of staff's website.
Since the 2011 civil war that ousted Muammar Gaddafi after 42 years of one-man rule, Libya has been unable to impose authority over brigades of former rebels who refuse to disarm and have carved out regional fiefdoms.
Benghazi, the cradle of the NATO-backed uprising against Gaddafi, in particular has struggled to curb violence and stem attacks blamed on Ansar al-Sharia, an Islamist group that Washington designates as a terrorist organisation.
Haftar, a leading figure in the 2011 uprising that ousted Gaddafi, stirred rumours of a coup in February by appearing in military uniform to call for a presidential committee to be formed to govern until new elections.
Libya's government is fragile and the parliament almost paralysed by rivalries, with little progress to full democracy made since 2011. A planned new constitution is still unwritten and the country is on its third prime minister since March.
U.S. and European countries are helping build up the regular army but Libya's armed forces and government cannot control the brigades of ex-rebels and militants who once fought Gaddafi.
The North African nation's vital oil industry has suffered badly and is often targeted by armed protesters seeking a greater share of oil wealth, federalist power for the regions or just better basic services.
Since last summer, armed protesters have repeatedly closed down ports and oilfields, bringing production down to around 200,000 barrels per day from the 1.4 million bpd that the OPEC member state produced before the protests erupted (Reporting by Feras Bosalum, Ahmed Elumami and Ayman al-Warfalli and Ulf Laessing; Additional reporting by Shadia Nasralla in Cairo; Writing by Ulf Laessing; Editing by Robin Pomeroy)