AWARAN, Pakistan (AFP) - A powerful 6.8-magnitude earthquake hit southwest Pakistan on Saturday, killing at least 22 people in a region already devastated by a tremor which left more than 300 people dead this week, local officials said.

"The death toll is increasing. Rescue workers have so far recovered 22 dead bodies," Mr Hari Fal, the top government official in Khuzdar town told AFP, adding that more than 50 people have been wounded.

Officials fear the toll in Saturday's quake in Awaran, the poorest district in the southwest province of Balochistan, could still rise further.

The new quake struck the remote district at a depth of 14km at 12:34 pm according to the US Geological Survey (USGS).

Although USGS said it was an aftershock of the Tuesday 7.7-magnitude quake, an official at the National Seismic Centre of Pakistan classified it as a new earthquake.

"It was not an aftershock, it was an independent earthquake," Mr Zahid Rafi, the centre's director, told Geo TV.

Awaran was shattered by the 7.7-magnitude quake on Tuesday which left 359 dead and more than 100,000 people homeless.

Relief efforts have at times been thwarted by insurgent attacks on rescue convoys, with local officials admitting that teams have been unable to reach thousands of survivors in the worst-hit areas.

"This new earthquake destroyed all that remains of the first quake, two villages destroyed completely," said Abdul Malik, provincial chief minister of Balochistan.

Pakistan's chief meteorologist Arif Mehmood told Express News that the magnitude of Saturday's quake measured 7.2.

Officials said villagers were digging through newly created debris and that dozens of wounded people have been taken to a make-shift hospital in Mashkey area, Awaran.

"The condition of some the injured was critical," doctor Asif Anwar told AFP from the makeshift hospital.

Deputy Commissioner of Awaran, Mr Abdul Rasheed Baloch told Geo TV that the second quake destroyed hundreds of mud houses in the Mashkey area, adding that "a lot of people have been trapped under the rubble".

"The telephone system has been damaged and we are not able to talk to someone and find out the exact information about the losses... But we have reports of severe losses in that area," Mr Baloch said.

An AFP reporter in Awaran said on Saturday that hundreds of patients being treated in the aftermath of the previous quake fled a hospital in panic as the new tremor hit.

Even before the latest quake struck, local officials said some 30,000 survivors were still waiting for aid.

As well as being remote, the area is a stronghold of Baloch separatist rebels waging a decade-long insurgency against the Pakistani state.

Since the Tuesday quake, insurgents have launched several attacks on rescue teams and issued threats.

On Thursday, a helicopter carrying the head of the NDMA came under rocket fire by insurgents while flying in Awaran district. No one was hurt and no damage was done.

On Friday, insurgents also opened fire on another helicopter and, in two separate incidents, fired on rescue convoys, officials said, adding that no one was hurt in the attacks.

The situation has forced officials to abandon efforts to reach survivors directly, saying instead they will work through village committees and private NGOs.

Mr Abdul Malik, provincial chief minister of Balochistan, told AFP that food and other rescue items would be distributed through local villagers.

He appealed to the local separatist groups to allow rescue officials to reach the survivors.

"It is a humanitarian tragedy and I appeal them to allow rescue workers to help the survivors," Mr Malik told AFP late on Friday.

Manan Baloch, a leader of the Baluchistan National Movement, allied to the Balochistan Liberation Front, told AFP that his group will only allow private NGOs and local officials to help survivors.

"We will not allow army or FC (paramilitary Frontier Corps) here, only NGOs or local officials are allowed to come here," he said.

A Pakistan army officer in Awaran told AFP the military only wanted to help locals.

"They are not ready to accept us," he said on condition of anonymity.

An AFP reporter in Awaran on Saturday said aid workers along with trucks loaded with food, clothes and medicine were seen moving towards Mashkey.