Libyan officials have said that eastern-based forces loyal to renegade military commander Khalifa Haftar have intensified their air attacks around Tripoli over the past two days.

Haftar’s self-styled Libyan National Army (LNA) launched an operation to take the capital from the UN-recognised Government of National Accord (GNA) on April 4 and has been engaged in fighting with its militias in and around the city.

LNA attacks on Monday targeted the Nawasi brigade in the Abu Salim district, located roughly 7km from central Tripoli, officials, who wished to remain anonymous, told The Associated Press news agency.

The Nawasi brigade is one of several militias allied with the internationally recognised GNA.

The towns of Khallet al-Forjan, Ain Zara and al-Twaisha along the city’s southern outskirts were also targeted.

Residents said that fighting continued overnight Sunday in residential areas a few kilometres south of Tripoli.

Both sides have used heavy artillery and air attacks, they said.

“We cannot move because of the shelling from both sides. Our homes have been damaged. We are trying to leave the area to a safer place,” said Mohammed al-Trapoulsi, a 41-year-old father of three from Abu Salim.

Reporting from Tripoli, Al Jazeera’s Mahmoud Abdelwahed said the LNA had advanced closer to the city centre on Monday.

“Forces loyal to Khalifa Haftar have advanced towards Al Sidra neighbourhood, about 15km away from Tripoli’s city centre. Eyewitnesses there say they have seen Haftar’s forces engaging against forces loyal to the UN-recognised GNA in the streets and in densely populated areas,” he said.

“In the past two weeks, Haftar’s forces were losing ground and the GNA’s forces were pushing them back. After they lost ground, Haftar’s forces intensified air strikes. The situation remains very tense, especially for civilians living in or near the fighting areas.”

On Sunday, GNA forces fought house-to-house battles with the LNA, pushing Haftar’s troops further away from the capital.

A Reuters news agency team visiting Ain Zara on Sunday said they estimated that forces allied to the Tripoli-based GNA gained up to 1,500 metres compared with a visit a few days prior.

Fathi Bashaga, the GNA’s interior minister, had on Friday announced that preparations were under way to mount a “full scale” attack against Haftar’s troops.

‘No Abraham Lincoln’

Separately on Monday, the United Nations envoy for Libya warned countries against backing Haftar and said his political agenda was not supported by most Libyans.

“He is no Abraham Lincoln, he is no big democrat, but he has qualities and wants to unify the country,” Ghassan Salame told France Inter radio, referring to the 19th century US president.

“But how is he going to do it? Seeing him act, we can be worried about his methods because where he is governing, he doesn’t govern softly, but with an iron fist.”

At least 278 people have been killed and more than 1,300 wounded in the clashes this month, according to a casualty toll released by the World Health Organization on Wednesday.

According to the International Organization for Migration, 39,000 people have been displaced by fighting along Tripoli’s southern districts.

The offensive, which Haftar said was aimed at cleansing Libya’s western region of “remaining terrorist groups”, has raised fears of a full-blown civil war in the oil-rich country, which has been mired in chaos since the NATO-backed toppling of long-time ruler Muammar Gaddafi in 2011.