AJDABIYAH, Libya (Reuters) - Muammar Gaddafi is using human shields to foil air strikes on his forces, NATO officials said on Wednesday as rebels angry at alleged Western inaction battled anew to advance on the key coast road.
In their eastern heartland, the ragged, ill-trained rebels set out again to recapture terrain lost in a headlong retreat from Gaddafi's superior firepower, reporting heavy fighting west of their frontline town of Ajdabiyah as both sides sought to end a seesaw stalemate in the oil-producing state's civil war.
Mohamed el-Masrafy, a member of a rebel special forces unit, said clashes broke out at 6 a.m. (0400 GMT) after government forces were resupplied with ammunition and rumbled eastwards out of the oil port of Brega, 80 km (50 miles) from Ajdabiyah.
NATO dismissed rebel complaints that its air strike campaign was slackening off, saying relieving the siege of Misrata, a rebel enclave in the west, remained the priority but conceding that Gaddafi's army was proving a resourceful, elusive target.
"The situation on the ground is constantly evolving. Gaddafi's forces are changing tactics, using civilian vehicles, hiding tanks in cities such as Misrata and using human shields to hide behind," spokeswoman Carmen Romero said in Brussels.
Western air power has fashioned a rough military balance in Libya, preventing Gaddafi troops from overrunning the motley rebel force dominating the east -- but not forceful enough for the insurgents to advance solidly hundreds of kilometers along the Mediterranean coast to the capital Tripoli in the west.
Masrafy told Reuters that the front line was about 20 km (12 miles) east of Brega, the focus of a weeklong to-and-fro battle. A sustained government assault on Tuesday drove rebels about halfway back to Ajdabiyah, gateway to their Benghazi powerbase.
Tuesday's pullback "wasn't a full withdrawal, it's back and forth," said Hossam Ahmed, a defector from Gaddafi's army as pick-ups loaded with machineguns and rocket launchers rolled westwards while several families fleeing the fighting in cars packed with their belongings passed in the opposite direction.
Journalists were banned on Wednesday from heading west from Ajdabiyah, making it difficult to assess the fighting.
Like other rebels, Ahmed expressed frustration at what he called NATO's hesitant approach. "There have been no air strikes. We hear the sound, but they don't bomb anything."
"WHAT IS NATO WAITING FOR?"
Said Emburak, an Ajdabiyah resident, chimed in: "What is NATO waiting for? We have cities that are being destroyed. Ras Lanuf, Bin Jawad, Brega, and Gaddafi is destroying Misrata completely."
French Foreign Minister Alain Juppe said NATO operations were at risk of getting "bogged down" due to the fact that Gaddafi's forces were frequently deploying close to civilians as tactical protection against air strikes.
He told France Info radio that he would address the issue shortly with the head of NATO, adding that Misrata's ordeal "cannot go on" but that "the situation is unclear."
Admiral Edouard Guillaud, France's armed forces chief, told Europe 1 radio: "I would like things to go faster but ... protecting civilians means not firing anywhere near them. That is precisely the difficulty."
He said NATO's six-day-old air campaign was concentrating on Misrata, where rebels were holding the port zone.
Misrata, under daily shelling, tank and sniper fire, is the only big population center in western Libya -- about 200 km (120 miles) east of Tripoli -- where a two-month-old popular revolt against Gaddafi has not been stamped out.
The inconclusive battlefield situation, defections from Gaddafi's coterie and the plight of civilians ensnared in fighting or running out of food and fuel has spurred a flurry of diplomacy in pursuit of a peaceful solution.
But such efforts have made little headway, with the rebels adamant that Gaddafi step down while the government, aware of the limitations of Western intervention, has offered concessions hinting at democratization but insists he stay in power.
NATO's air strikes are targeting Gaddafi's military infrastructure but only to protect civilians, not to provide close air support for rebels, while enforcing a no-fly zone and an arms embargo under a U.N. Security Council mandate.
Abdel Fattah Younes, head of Libya's rebel army accused NATO of being too slow to order air strikes to shield civilians, allowing Gaddafi's forces to slaughter the people of Misrata.
"NATO blesses us every now and then with a bombardment here and there, and is letting the people of Misrata die every day. NATO has disappointed us," he told reporters in the insurgents eastern stronghold city of Benghazi on Tuesday.
The conflict in the oil-producing North African state ignited in February when Gaddafi tried to crush pro-democracy rallies against his 41-year rule inspired by uprisings that have toppled or endangered other autocrats across the Arab world.
NATO has denied rebel assertions hat the pace of air strikes has abated since it took over the task from a smaller big power coalition of the United States, Britain and France on March 31.
"The assessment is that we have taken out 30 percent of the military capacity of Gaddafi," Brigadier General Mark van Uhm, a senior NATO staff officer, said in Brussels on Tuesday.
Younes said rebels were considering referring what he said was slow decision-making by NATO to the U.N. Security Council. "NATO has become our problem," he said, and in the meantime "Misrata is being subjected to a full extermination."
A U.S. envoy has arrived in Benghazi to get to know the opposition and discuss possible financial and humanitarian assistance, a U.S. official said. The visit by Chris Stevens, former deputy chief of mission at the U.S. embassy in Tripoli, reflects a U.S. effort to deepen contacts with the insurgents.
Turkey, whose status as a secular Muslim state positioned between Europe and theMiddle East gives it unusual mediating potential, also sent a special envoy to Benghazi for talks with the opposition, its foreign minister said.
(Additional reporting by Brian Love and Nick Vinocur in Paris, Daren Butler in Istanbul,Angus Macswan in Benghazi, Arshad Mohammed and Mark Hosenball in Washington; writing by Mark Heinrich; editing by Giles Elgood)