Tens of thousands of survivors of Pakistan's earthquake waited for help in soaring temperatures Thursday, as the death toll rose past 350 and anger grew at the slow pace of government aid.

More than 100,000 people made homeless by Tuesday's 7.7-magnitude quake spent a second night in the open or under makeshift shelters as response teams struggled to reach the remote region in the southwestern province of Baluchistan.

"At least 357 people died and 620 others injured," the Provincial Disaster Management Authority said in Quetta.

It said 311 people died in Awaran district, where the quake struck, and 46 were killed in neighbouring Kech district.

The sheer scale of the territory involved is daunting -- the population of Awaran is scattered over more than 21,000 square kilometres (8,000 square miles) of remote and rugged terrain -- and infrastructure is extremely limited, with few medical facilities or even roads.

The area is also home to Baluch separatist rebels waging a decade-long insurgency.

Highlighting the danger from militants, a helicopter carrying the head of the National Disaster Management Authority came under rocket fire in Awaran, though no damage was done and no one was hurt.

Hours later paramilitary troops helping the relief effort were fired at with small arms by suspected rebels, around 20 kilometres (12 miles) north of Awaran, but there were no casualties, a senior security official told AFP.

The quake is Pakistan's deadliest since the devastating Kashmir tremor of 2005 which killed 73,000. The toll is expected to rise further as rescue teams dig through the rubble of countless flattened mud-brick homes.

Interior Minister Chaudhry Nisar told parliament "huge activity" was under way to help those affected but he admitted teams were struggling to reach some areas, even 40 hours after the quake.

The army has sent troops, medical staff and helicopters to help with rescue efforts, along with seven tonnes of food and a tonne of medicine.

The government is preparing to send more than 14,000 tents, Nisar said, and is using a C-130 transport plane to reach difficult areas.

In Arawan town, around 200 angry survivors demonstrated outside government offices complaining they had not been given food or shelter.

Survivors in Gajjar, some 120 kilometres east of Awaran, where the quake killed at least 108 people, said they were forced to scavenge for food, complaining of a lack of government aid.

"The government is completely missing and we have not received a single relief item like tents or food," survivor Abdul Razzaq told AFP.

Abdul Rasheed, an other survivor in nearby Khaliq Abad said residents were raking through rubble to find biscuits to feed their children.

"I dug out biscuits from the dust from the rubble of my shop and gave it to my children as we have nothing to eat and we are eating raw barley to survive," Rasheed told AFP.

At a local madrassa administrator Hafiz Muhammad Ashraf showed AFP a mass grave of 22 female students who were buried in the rubble of the Muslim seminary.

An AFP reporter saw activists of the Baluchistan National Movement (BNM), a separatist party, helping the relief effort along with banned charity Jamaat-ud-Dawa (JuD), which is blamed for the 2008 Mumbai attacks that left 166 people dead.

Temperatures in the arid region were reaching 42 degrees Celsius (108 Fahrenheit) and many survivors said they were desperate for some relief from the blistering heat.

The provincial disaster official Kakar said the quake had left more than 100,000 people homeless in Arawan, a dirt-poor expanse of land roughly the size of Wales.

Besides flattening homes and affecting more than 300,000 people in six districts, according to the Baluchistan government, the earthquake even created a new island about 650 feet off the coast.