The leader of the besieged Libyan rebel city of Misrata has appealed to Nato to save the inhabitants of a neighbouring town facing annihilation from government forces.

Sheikh Khalifa Zuwawi, chairman of Misrata council, made the appeal through the Guardian on Wednesday after reports that Muammar Gaddafi had demanded that rebel-held areas of Zlitan, 30 miles west of Misrata, surrender or face destruction.

Zlitan's uprising began on Friday with battles around the town's hospital, but sources in Misrata say the rebels are now pinned into one district under heavy artillery fire.

Photographers who got to within four miles of Zlitan on Tuesday took pictures of government rockets exploding in the town.

Misrata's rebel forces say that without heavy weapons or Nato support they are powerless to break through a fortified ring around the town and save residents.

"As you know our forces could not get into Zlitan," said Zuwawi. "We need Nato help. We are very surprised because Nato has delayed to bomb the grad [rocket artillery] forces."

Zlitan lies along the coastal highway from Misrata, about 100 miles east of Tripoli, and rebel commanders say its capture would open the road to the capital.

But they face formidable foes in the shape of the elite 32nd brigade, controlled by Gaddafi's son Khamis, which has made Zlitan its headquarters.

On Tuesday rebel forces in Misrata pushed their frontline forwards five miles to try and relieve Zlitan, coming under fire from machine guns and rockets. But they pulled back after Nato, unaware of the advance, dropped leaflets on the area threatening pro-Gaddafi forces with destruction from Apache helicopters if they continued attacks on civilians. The Nato attacks have yet to materialise despite pro-Gaddafi forces bombarding Zlitan and Misrata late on Tuesday.

Nato insists it is taking an active role, but Misrata's rebels say the alliance's current level of engagement will not be enough to save Zlitan's population.

Zuwawi, a judge, said that the National Transitional Council (the rebel government) was surprised at the delay, adding that Nato needs to apply UN resolution 1973, authorising the use of force to protect Libyan civilians, he added.

In the village of Dafniya, the western-most point of Misrata's frontline, rebels and civilians on Wednesday said they were baffled that Nato had not followed up on its threats, given the overnight shelling by Gaddafi's forces.

"No Nato," said Mohammed, the 14-year-old son of a Dafniya rebel fighter drinking tea behind one of the giant sand berms that shield rebel positions from sniper fire. "Where is Nato?"