|Rebel fighters have been engaging with Gaddafi forces in Zlitan, Nafusa and Brega in recent days [AFP]
Fighting has broken out in the western Libyan town of Zlitan, after rebel forces say troops loyal to Libyan leader Muammar Gaddafi launched an offensive on their positions in the town's suburbs.
Several rebel fighters told Al Jazeera that they were taken off guard during the offensive early on Tuesday morning, and that Gaddafi's forces had used tanks to launch an "all out offensive," outflanking rebel positions on the outskirts of the town.
At least seven rebel fighters were killed and a further 50 wounded in the fighting, opposition forces said.
"At this particular moment I can't tell you how much [the rebels] pulled back," said Al Jazeera's Hoda Abdel-Hamid, reporting from Misrata, where many of those wounded during the fighting were being treated.
"Earlier, several fighters told me they had pulled back - the situation is still extremely fluid."
Abdel-Hamid reported the hospital at Misrata as being "overwhelmed" by the casualties.
Colonel Ahmed Omar Bani, a Benghazi-based spokesman for the rebels' military, told the AFP news agency that the opposition forces had launched a counter-offensive in Zlitan, and were involved in a "vicious fight" with pro-Gaddafi forces in the centre of the city.
Bani said that clashes also took place in the eastern oil town of Brega on Tuesday, where the rebels fought with pro-Gaddafi forces for several hours before being forced to retreat.
Abdel-Hamid said that Zlitan, as the last major town left in government hands to the east of Tripoli, would be a key strategic gain for the rebels, but that they face several difficulties in taking the town.
For one, she said, Gaddafi's forces are present there "in large numbers", with reports of the Libyan army's 32nd Brigade being deployed there.
Second, the rebels have been "receiving very mixed messages from the residents of Zlitan," she said.
While some residents told rebel fighters that they are openly pro-Gaddafi, others have told them that they will receive support if they attempt to take the town, she said.
Rebel fighters say that they would only enter the town if they receive an "invitation" from the local tribes.
Russia, meanwhile, said on Tuesday that the fighting in Libya has reached a "dead end", and that all parties should seek "political and diplomatic solutions".
"The situation has reached a dead end that confirms that there is no military solution," Sergei Vershinin, the head of the foreign ministry's Middle East and North Africa department, was quoted as saying by the Interfax news agency.
"We have to go back to searching for political and diplomatic solutions."
The opposition has been rooting out what they say are pro-Gaddafi agents within its own ranks in their eastern bastion, while fighting on the Zlitan, Brega and Nafusa fronts continues.
At least 63 people suspected of having links to Gaddafi, and of murdering the rebels' military chief last week, were rounded up by the rebels on Sunday and Monday, the opposition said, following an hours-long battle in the opposition stronghold of Benghazi.
Security forces patrolled the streets in a bid to track down more members of the pro-Gaddafi group, a rebel spokesman said.
Opposition forces have captured the base of the Gaddafi loyalists, called the al-Nidaa Brigade, an armed group which had been operating under the opposition's banner, spokesman Mahmoud Shamam said.
Medics said at least four opposition members and 11 pro-government troops were killed in the clashes.
Al Jazeera's Tony Birtley, reporting from Benghazi, said the battle was launched to subdue elements of Gaddafi's forces that had been operating as a "fifth column" within the opposition ranks.
The fighting followed Thursday's killing of Younes, the chief rebel commander, under mysterious circumstances.
On Tuesday, rebel leaders told the AFP news agency that they had found a "hit list" of 60 rebel leaders during their raid of the al-Nidaa Brigade's base.
"There were around 60 people (on the list)," Mustafa al-Sagisli, the rebels' deputy interior minister, told AFP, including "members of the [National Transitional Council], the military council, the cabinet of the NTC executive."
"There were names and addresses," he said, "some of the addresses were correct."
Fighting in Nafusa mountains
Forces loyal to Gaddafi, meanwhile, took control on Monday of the village of al-Jawsh at the foot of the strategic western Nafusa mountains, AFP journalists at the scene said.
The rebels had on Sunday taken the village, but said they were forced to retreat to the east, half way along the road to the town of Shakshuka, after several hours of fighting.
The rebels said al-Jawsh had been emptied of residents and pro-Gaddafi forces were now in the village.
The Nafusa region has seen heavy fighting between rebels and forces loyal to Gaddafi since the rebels launched a major offensive this month in a drive on the capital Tripoli.