(In paragraph 7, corrects spelling of Tripoli suburb to Ain Zara, not Ain Sara)
* Eastern forces' bid to seize Tripoli stalls on outskirts
* 56 dead, over 8,000 forced to flee capital -United Nations
* Italy, ex-colonial power, and France back opposing sides
By Ulf Laessing and Giselda Vagnoni
TRIPOLI/ROME, April 11 (Reuters) - France and Italy wrangled on Thursday over how best to tackle renewed conflict in Libya as a bid by eastern forces under Khalifa Haftar to seize Tripoli stalled in the face of strong resistance on the capital's southern outskirts.
The United Nations said the fighting between Haftar's forces and troops under the internationally-backed Tripoli government had killed at least 56 people and forced 8,000 to flee their homes in the city in the last week.
A Reuters reporter heard occasional heavy gunfire and explosions as the eastern Libyan National Army (LNA) faced off with forces of Prime Minister Fayez al-Serraj's government around the ex-international airport and the Ain Zara district.
Officials brought families displaced by fighting on Tripoli's southern fringes to area schools. Red Crescent workers were heading out rations in one school as gunfire clattered in the distance.
Haftar's push on Tripoli in Libya's northwest is the latest turn in a cycle of factional violence and chaos in Libya dating back to the 2011 uprising that overthrew veteran dictator Muammar Gaddafi.
After sweeping up from the south, LNA became bogged down in Tripoli's southern suburbs 11 km (7 miles) from the city center. Several locations have changed hands more than once.
More than 190 LNA troops were captured, officials in Tripoli said, accusing it of using teenagers. A total of 116 fighters were captured in Zawiya, a town west of Tripoli, and an additional 75 in Ain Zara on the southern outskirts of the capital, officials said.
In a prison in Zawiya, Reuters reporters saw prisoners, mostly young men, some wearing civilian clothes, sitting on the floor of a prison while others stood with their faces turned to a wall.
In Rome, Libya's former colonial ruler Italy warned France, which has good relations with Haftar, to refrain from supporting any one faction after diplomats said Paris had scuttled a European Union statement calling on him to halt his offensive.
"It would be very serious if France for economic or commercial reasons had blocked an EU initiative to bring peace to Libya and would support a party that is fighting," Deputy Prime Minister Matteo Salvini told Radio RTL 102.5.
"As minister of the interior I will not stand by and watch."
France, which has oil assets in eastern Libya, has provided military assistance in past years to Haftar in his eastern stronghold, Libyan and French officials say. It was also a leading player in the war to unseat Gaddafi..
Italy supports the U.N.-backed government of Serraj.
ITALY SPARS WITH FRANCE
"Some think that the (2011 Nato-led military intervention) in Libya promoted by (then-French President Nicolas) Sarkozy was triggered more by economic and commercial interests than by humanitarian concerns," Salvini said.
"I hope we are not seeing the same film all over again."
An EU draft statement on Wednesday said Haftar's attack on Tripoli put civilians at risk, disrupted normalization efforts and risked an escalation with serious consequences for Libya and the wider region. That statement was sidelined by France .
French diplomatic sources said Paris did not object to calls on Haftar to halt his advance, but rather had only requested amendments including mentions of the plight of migrants in Libya and the presence in anti-Haftar forces of Islamist militants designated as terrorists by the United Nations.
The latest tally of casualties from the U.N. World Health Organization (WHO) said 56 people - mainly combatants though also some civilians including two doctors and an ambulance driver - had been killed, and another 266 wounded in Tripoli.
In addition, 28 LNA soldiers had been killed and 92 wounded since the start of the offensive a week ago, according to the LNA.
The number of people forced out of their homes by fighting rose to 8,075, the U.N. migration agency IOM said.
As well as the humanitarian consequences, renewed conflict in Libya threatens to disrupt oil supplies, increase migration across the Mediterranean to Europe, scupper the U.N. peace plan for the country and encourage militants to exploit the chaos. Libya is a main transit point for migrants who have poured into Europe in recent years, mostly by trafficking gangs.
The LNA forces swept out of their stronghold in eastern Libya to take the sparsely populated but oil-rich south earlier this year, before heading towards Tripoli, where Serraj's U.N.-backed government sits.
Haftar was among the officers who helped Gaddafi seize power in a 1969 coup before parting ways with him later. But critics call Haftar another strongman in Gaddafi's mould.
Haftar has resisted U.N. pressure to accept a power-sharing settlement to stabilize the country, using his leverage as a Western ally against militant Islam in North Africa. (Additional reporting by Ahmed Elumami in Tripoli, Tom Miles in Geneva and John Irish in Paris; Editing by Mark Heinrich)