* At least four dead in new clashes in Benghazi
* Renegade general's forces target Islamist camps
* General slams Qatar role in Libya, praises Egypt (Adds death toll, power cut off, Haftar comments)
By Ayman al-Warfalli and Ahmed Elumami
BENGHAZI/TRIPOLI, Libya, June 15 (Reuters) - A renegade Libyan general launched a fresh offensive on Sunday against Islamist militants in the eastern city of Benghazi, sparking some of the worst fighting in weeks in which at least four people were killed and power supplies disrupted.
Libyan authorities are struggling to restore order across the vast desert nation ahead of a June 25 parliamentary election. The situation remains especially chaotic in Benghazi, Libya's second largest city and cradle of the NATO-backed uprising that toppled Muammar Gaddafi three years ago.
Retired general Khalifa Haftar has declared war against militants in Benghazi and several army units have joined him. The Tripoli government says he has no authority to act but its orders are routinely ignored in much of the country, especially the east, as rival militias and tribal groups vye for control.
Haftar's troops, backed by tanks and rocket launchers, attacked several suspected camps of Islamists in western areas of Benghazi on Sunday, forcing dozens of families to flee. War planes could also be heard circling above the city.
Benghazi and much of eastern Libya suffered power outages after rockets hit a power station near the city's airport, the state electricity firm said.
There has been speculation among analysts that Haftar has the support of neighbouring Egypt and of Gulf states such as the United Arab Emirates, which like the West is worried about Islamist militants exploiting the chaos in Libya.
Haftar told Saudi-owned Arabiya television that his forces were being supported by Libya's neighbours to help secure the country's borders, according to the channel's website. He did not elaborate and he later issued a denial of any such support.
HAFTAR SLAMS QATAR, LAUDS EGYPT
At a news conference held outside Benghazi, Haftar praised Egypt's new president, Abdel Fattah al-Sisi, as the right man for the job. Egypt has cracked down hard on the Islamist Muslim Brotherhood, which Haftar on Sunday branded as an "international spy network".
Haftar also accused Qatar of fueling Libya's chaos. "There is no doubt Qatar supports the militias in Libya," he said.
Separately, he told Arabiya television Qatar was hampering the formation of a national army and police force in Libya.
Qatar has come under pressure from Gulf states such as Saudi Arabia, the UAE and Bahrain over its backing for the Muslim Brotherhood. All three withdrew their ambassadors to Doha in March, causing an unprecedented public rift in the Gulf.
The latest fighting in Libya comes less than two weeks before a parliamentary election that ordinary citizens hope will bring an end to the chronic political infighting that has paralysed decision-making since the last vote in summer 2012.
Western powers and Gulf countries fear that Islamists will turn Libya into a battlefield or transit point for fighters heading for conflict zones such as Egypt's Sinai, Syria or sub-Saharan countries like Mali.
The security fears are particularly acute for Benghazi, home to several oil firms and the focus of Haftar's campaign.
Haftar's spokesman Mohamed El-Hejazi said Haftar had warned the Islamists against shipping in arms via the commercial port of Derna, east of Benghazi. Derna is a focal point for Ansar al-Sharia, a militant group designated as terrorist by the United States, and other insurgents.
Haftar was once close to Gaddafi but fell out with him and then played a role in the 2011 uprising. In February, he stirred rumours of a coup by appearing in army uniform to call for a presidential committee to be formed to govern till an election. (Writing by Ulf Laessing; Editing by Gareth Jones)