* Gaddafi's birthplace Sirte is rebels' next target
* Russia says intervening on rebel side breaches U.N. terms
* Qatar recognises rebels as representatives of Libya
(Updates situation in Sirte)
By Angus MacSwan
BIN JAWAD, Libya, March 28 (Reuters) - Rebels advanced towards the birthplace of Libyan leader Muammar Gaddafi on Monday, streaming west along the the main coastal road in pick-up trucks mounted with machineguns.
Russia criticised the Western-led air strikes that have turned the tide of Libya's conflict, saying these amounted to taking sides in a civil war and breached the terms of a United Nations Security Council resolution.
Qatar became the first Arab country to recognise the rebels -- now in the sixth week of their uprising against Gaddafi's 41-year rule -- as the sole legitimate representative of the Libyan people.
Al Jazeera said the rebels had seized the town of Nawfaliyah from forces loyal to Gaddafi, extending their advance westwards towards his hometown of Sirte, about 120 km (75 miles) away.
Emboldened by the Western-led air strikes against Gaddafi's forces, the rebels have quickly reversed earlier losses and regained control of all the main oil terminals in the east of the OPEC member country.
"We want to go to Sirte today. I don't know if it will happen," said 25-year-old rebel fighter Marjai Agouri as he waited with 100 others outside Bin Jawad with three multiple rocket launchers, six anti-aircraft guns and around a dozen pick-up trucks with machineguns mounted on them.
A Reuters correspondent who was about 15 km (10 miles) west of Bin Jawad on the road to Nawfaliyah heard a sustained bombardment on the road ahead.
"This is the frontline. The army has stopped over there, we are stopping here," Mohammed al-Turki, 21, a fighter at a rebel checkpoint, told Reuters, pointing to the road ahead where the sounds of blasts were coming from.
Western-led air strikes began on March 19, two days after the U.N. Security Council authorised "all necessary measures" to protect civilians from Gaddafi's forces. But since the outset, the mission has faced questions from critics about its scope and aims, including the extent to which it will actively back the rebel side and whether it might target Gaddafi himself.
Russia, which abstained in the U.N. vote, said Western attacks on Gaddafi's forces amounted to taking sides with the rebels.
"We consider that intervention by the coalition in what is essentially an internal civil war is not sanctioned by the U.N. Security Council resolution," Foreign Minister Sergei Lavrov told a news conference.
Russian oil company Tatneft is expected to book $100 million of losses on capital expenditure in Libya as a result of the conflict, a company source told Reuters.
NATO chief Anders Fogh Rasmussen told the BBC: "We are there to protect civilians -- no more, no less."
Contradicting a rebel claim to have captured Sirte, Reuters correspondent Michael Georgy reported from the city that the situation was normal. He had seen some police and military, but no signs of any fighting.
Soldiers were manning checkpoints and green Libyan flags flapped in the wind. Militiamen fired AK-47 rifles defiantly into the air. "If they come to Sirte, we will defend our city," said Osama bin Nafaa, 32, a policeman.
As Gaddafi's hometown and an important military base, Sirte -- about half-way along the coast from the rebel stronghold of Benghazi to Tripoli -- has great symbolic and strategic value.. If it fell, the rebels would gain a psychological boost and the road towards the capital would lie open.
As the rebels pressed forward in the east, they reported attacks by Gaddafi's forces in the west. One rebel spokesman told Al Jazeera that loyalist forces bombarded the rebel-held city of Misrata again on Monday, and snipers were on rooftops. Another told Al Arabiya television that eight people had been killed and more than 24 injured in clashes.
A rebel spokesman in another western town, Zintan, said forces loyal to Gaddafi bombarded the town with rockets early on Monday, Al Jazeera reported.
Libya's state news agency Jana said Western forces bombed the southern city of Sabha at dawn on Monday, leading to several casualties.
At least six blasts resonated in Tripoli on Sunday night, followed by long bursts of anti-aircraft fire by Libyan forces. Libyan television said there had been air strikes on the "civilian and military areas" in the capital.
Libyan state TV broadcast what it said was live footage of Gaddafi in a car in his Tripoli compound where hundreds of supporters waved green flags and chanted slogans. Gaddafi could not be seen in the white car but the TV said he was in it.
On Sunday, NATO agreed to take full command of military operations in Libya after a week of heated negotiations, officials said. The United States, which led the initial phase, had sought to scale back its role in another Muslim country after the wars in Iraq and Afghanistan.
U.S. Defense Secretary Robert Gates said Western air strikes had "eliminated" Gaddafi's ability to move his heavy weapons.
Gates also raised the possibility that Gaddafi's government could splinter and said an international conference in London on Tuesday would discuss political strategies to help bring an end to Gaddafi's rule.
Libya accused NATO of "terrorising" and killing its people as part of a global plot to humiliate and weaken the North African country.
The government says Western-led air attacks have killed more than 100 civilians, a charge denied by the coalition which says it is protecting civilians from Gaddafi's forces and targeting only military sites to enforce the no-fly zone.
"The terror people live in, the fear, the tension is everywhere. And these are civilians who are being terrorised every day," said Mussa Ibrahim, a Libyan government spokesman.
"We believe the unnecessary continuation of the air strikes is a plan to put the Libyan government in a weak negotiating position. NATO is prepared to kill people, destroy army training camps and army checkpoints and other locations."
Britain's Guardian newspaper quoted Turkish Prime Minister Tayyip Erdogan as saying his country was ready to act as mediator and broker an early ceasefire.
Erdogan said if the parties to the conflict requested Turkey to mediate, "we will take steps to do that" within the framework of NATO, the Arab League and the African Union. (Additional reporting by Alexander Dziadosz, Edmund Blair, Maria Golovnina, Michael Georgy, Ibon Villelabeitia, Tom Pfeiffer, Lamine Chikhi, Mariam Karouny, Joseph Nasr, Marie-Louise Gumuchian, David Brunnstrom and Arshad Mohammed; Writing by Mark Trevelyan; Editing by Giles Elgood)