The hotel does not even have a name. It was finished but never opened because of the outbreak of the Libyan revolution earlier this year. These days it serves as one of the bases of the revolutionary forces attempting to take Sirte from some of the last loyalists of the Gaddafi regime.

The stairs to the seventh floor roof terrace are spotted with blood. The large windows, with views on to the Mediterranean and the beach below, have been blown out by sniper fire.

From the roof terrace itself, where a spotter surveys the sniper positions from behind sandbags to call in tank fire, the besieged coastal city is visible below.

To one side the highway that runs alongside the sea is empty, save for the armed trucks of the forces of Libya's new government.

On this, the east side of the city, the fighters are largely from the east – from Benghazi and cities like Bayda.

Straight ahead, however, is a collection of buildings near the Ibn Sana hospital – two miles (3km) away – which has become the target of the tanks, rocket launchers and anti-aircraft guns of Libya's revolutionaries, lined up on the low sandy ridge that overlooks the town.

On Thursday a pall of white smoke hung across this district as shells exploded every few minutes, and people in the hotel warned of a sniper firing from the minaret of a mosque 500 metres away from the hotel.

"We want to get this thing finished quickly," said a young bearded fighter standing by the wrecked lifts. "We had a plan to try and open the road to the hospital to evacuate civilians, but there were too many snipers. Yesterday we tried many times to open the road."

It is a reflection of the nature of Libya's last battle. The new government has said it will announce full liberation when Sirte is taken, even though a second town – Bani Walid – has also yet to fall.

But it is on the fall of Sirte that all expectations have been pegged.

The battle is a ramshackle affair. On the west side of the city, where the katibas [rebels] from Misrata launch almost daily attempts to take the Gaddafi stronghold of the Ougadougou conference centre, the fighters gathered for an impromptu breakfast outside a little field hospital. On Thursday they had poured in behind three tanks only to be driven back by missiles.

On the east side of Sirte, reached via a dirt road that skirts the city, the forces appear more organised. In the morning, a group met at a roundabout on the outskirts of the city, close to where a tank was pounding the buildings below. A burst of bullets came across the roundabout, sending the men scuttling for cover.

"Yesterday the Gaddafi forces come up to the roundabout with an anti-aircraft gun and fired at us," said Salam Farjani, 37, who came to Sirte from Bayda. There were no civilians around at this time; Farjani explained that they try to leave early in the morning and at dusk, when it is safer.

"The ones who are left are the ones who have no petrol for their cars," he said. "And the Gaddafi fighters in the town are just fighting for their survival.

Salay Abiydi leads us up to an unfinished house overlooking the city. "See the buildings behind the hospital? Most of Gaddafi's military is there. They have surrounded them with truck containers filled with sand. We have their radio frequency."

There is no water, electricity or petrol. People who come out of Sirte – including deserters – say everything is very expensive. Even a cigarette lighter costs four dollars.

"When we see deserters, sometimes they try to come out with their families, but we find a pistol or papers saying who they are. They know it is finished. The last deserter that we had was a week ago from Gaddafi's tribe," said Abiydi.

And while many have fled or are trying to flee the bombardment of Sirte, not all of those who want to will be able to get out before the government forces launch their long-threatened final assault.

"We don't expect to evacuate all of the city," said Saleh Jabou, commander of one of the revolutionary katibas, the Lions of the Wadi. "We will still attack and that will be in a few days. We have people still trying to negotiate, but Gaddafi's people – if they reply – say just give us more time."

The latest heavy fighting in Sirte came as the Red Cross said it was communicating with both sides but struggling to deliver aid because of the danger of operating in the city. "We barely manage to drive in," said Dibeh Fakr, at a field hospital in a mosque on the outskirts of the city. "We deliver the items and get out, because the security situation is so bad and we can be targeted and may be caught in the shooting."

The battle for Sirte has come at a high cost for civilians. They are trapped, with dwindling supplies of food and water and no proper medical facilities to treat the wounded. Many residents are members of Gaddafi's own tribe and those fleeing the city blamed the death and destruction on the forces of the new government, and the Nato alliance, whose warplanes have been flying sorties over the city.

Hajj Abdullah, in his late 50s, was at a Red Cross post on the edge of Sirte where food was being handed out, explaining he had just escaped the city. "My 11-year-old died from the Nato rockets … I buried him where he died," he told Reuters, "because it was too dangerous to go to the cemetery. There are random strikes in the city. People are dying in their houses."