Libya's IS fighters make their final stand in Sirte
Sirte has witnessed two days of heavy fighting as IS fighters prepare to make their final stand in the hometown of former Libyan leader Muammar Gadaffi on the coast.
Militias loyal to the Tripoli-based Government of National Accord launched an offensive on Sirte more than three months ago to destroy the IS bastion which posed a threat to the country's oil supplies and threatened to expand deeper into Libya.
Their assault has been helped by US air raids in the past month of the offensive.
Suicide attacks
Since then, pro-government fighters have taken over most of Sirte but in recent days faced stiff resistance from the remaining IS fighters, including waves of suicide bomb attacks and sniper fire.
Pro-government forces fought back with tanks and artillery.
Tripoli's forces announced that they had "totally liberated" one of the two districts where around 1,000 IS fighters were holed up.
The cost has been heavy for pro-Tripoli forces. At least 38 pro-government fighters were killed on Sunday and another 185 injured, AFP reported.
A further ten died in fighting on Monday, while nearby Misrata hospital is stuggling to deal with the casualties.
"It was a bloody day," doctor Akram Jumaa said.
"I carried out dozens of surgeries that lasted until this morning, and some others are still ongoing."
Many dead
Mohammad Quweid, a nurse, bemoaned the lack of means to treat casualties.
"There aren't enough rooms so sometimes we have to put five or six fighters together in the same room."
"Our forces have totally liberated district Number One," the campaign's media centre said.
"The price was costly but they liberated it," Reda Issa, a spokesman for the loyalist forces, told AFP.
More than 400 loyalist fighters have been killed and nearly 2,500 wounded in the battle for Sirte since May, and that figure is set to rise.
The thousand or so IS militants are now confined to half of district Number Three in the east of the city, and around 30 percent of district Number One.
Rule by fear
Among the positions captured by Tripoli forces in district Number Three was the Qortoba mosque renamed after the former al-Qaeda in Iraq leader Abu Musab al-Zarqawi, who inspired similar fear.
Since IS militants took over Sirte in June 2015, their reign has been bloody and cruel.
Once they established their rule, jihadis set fire to the mosque's library, killed an imam and used its courtyard for "torture and executions", the pro-government forces have discovered.
However, the militants' hold on the city was fairly secure due to the inter-governmental struggle, with moderate militias fighting one another.
That was until the formation of an interim government in Tripoli in December, which received Western and UN backing.
Most of the militias are from western cities backing the unity government of premier-designate Fayez al-Sarraj.
They are also joined by the relatively professional guards of oil installations that IS has repeatedly tried to seize.
Backed by US air strikes since 1 August, they seized the IS headquarters at the Ouagadougou conference centre on 10 August, pinning down IS fighters near the sea.
US warplanes have carried out 82 strikes, supporting the anti-IS ground forces.
Analysts say ousting IS from Libya would be a symbolic boost for the fragile unity government, but unrest might continue as IS could carry out more scattered attacks across the country.
Before it was seized by IS, Sirte had a population of around 120,000 residents.
The pro-unity goverment military leader believes that almost all of city's the residents had fled, leaving Sirte with just the jihadis and their families remaining in what has become Libya's most intense battleground.
Agencies contributed to this story.