Forces loyal to Libya's interim government say they have captured the airport in Sirte, the birthplace of the former Libyan leader Muammar Gaddafi.

Fighters belonging to National Transitional Council said on Wednesday they were in control of the airport after intense fighting in the coastal city, one of the last of two bastions of support for the deposed Libyan leader.

Sirte has withstood a siege by NTC fighters hitting it with tank and rocket fire as well as NATO air raids.

But intense sniper and artillery fire from pro-Gaddafi forces has so far prevented NTC forces from taking Sirte, despite more than two weeks of fighting and two full-on assaults.

Al Jazeera's Zeina Khodr, reporting from the city, said the latest seizure by NTC forces marked the capture of a strategic site.

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"Anti-Gaddafi fighters seem to be in control of Sirte airport, a very strategic location; they have been receiving help from NATO," she said.

But our correspondent said that NTC fighters have not been able to hold territory inside Sirte. 

"They are outside the town, there have been major clashes since Saturday but they couldn't maintain territory [and] they had to retreat," she said.

"One has to remember that Gaddafi has supporters in Sirte, he has fighters, mercenaries. volunteers and they are all armed."

Concern for civilians

Amid the fighting, the UN and international aid agencies have expressed concern over conditions for civilians trapped inside.

Our correspondent said:"People that are trapped in Sirte have told us that the situation is dire, there is no electricity or water. The hospitals have no medicine and no staff.

"The NTC are concerned about the people that are trapped in Abu Hadi, they are from across the country. They don't have water or electricity, it seems like they have been used as human shields.

"There is a an urgency for the fighters to take over Sirte as soon as possible."

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It has been more than a month since NTC fighters captured the capital Tripoli, and Gaddafi remains defiantly on the run, pledging to lead a campaign of armed resistance against the new leaders.

Lack of co-ordination and divisions on the front have hampered NTC attempts to capture Sirte and the other bastion of Gaddafi's control, Bani Walid.

Gaddafi is believed to be holed up near the western town of Ghadamis near the Algerian border under the protection of Tuareg tribesmen, a senior NTC military official has said. 

"There has been a fight between Tuareg tribesmen who are loyal to Gaddafi and Arabs living there [in the south].

"We are negotiating, the Gaddafi search is taking a different course," Hisham Buhagiar told the Reuters news agency.

Many Tuaregs, nomads who roam the desert spanning the borders of Libya and its neighbours, have backed Gaddafi since he supported their rebellions against the governments of Mali and Niger in the 1970s and allowed them to settle in Libya.

Buhagiar said Gaddafi's most politically prominent son, Saif al-Islam, was in Bani Walid, and that another influential son, Mutassem, was in Sirte.

Source: Al Jazeera and agencies