Around 20 people were killed and dozens seriously injured when a shallow earthquake hit southern Pakistan in the early hours of Thursday as people slept, government officials said.

Many of the victims died when roofs and walls collapsed after the 5.7 magnitude quake struck, with health workers treating the injured with the help of torches after electricity failed.

A woman and six children were among 20 dead, Suhail Anwar Hashmi, a senior provincial government official, told AFP.

"We are receiving information that 20 people have been killed due to the earthquake. Rescue efforts are under way," provincial interior minister Mir Zia ullah Langau added.

Naseer Nasar, the head of Balochistan's Provincial Disaster Management authority, told AFP that between 15 and 20 people had died, but warned that the toll may increase.

The worst-affected area was the remote mountainous city of Harnai, in Balochistan, where a lack of paved roads, electricity and mobile phone coverage has hampered the rescue effort.

The quake caused electricity to fail in the region, with health staff working without lights in a poorly equipped government hospital.

Pakistan
Map locating a 5.7 magnitude earthquake that hit southern Pakistan in the early hours of Thursday. Photo: AFP / STAFF

"We were operating without electricity with the help of torches and mobile flashlights," Zahoor Tarin, a senior official at the government-run Harnai hospital told AFP.

"Most of the injured came with fractured limbs. Dozens of people were sent back after first aid while some 40 people who were critically injured have been sent to Quetta in ambulances," he added.

The US Geological Survey said the quake had a magnitude of 5.7 and struck around 3am at a depth of around 20 kilometres (12 miles).

The earthquake was also felt in Balochistan's provincial capital Quetta.

Pakistan straddles the boundary where the Indian and Eurasian tectonic plates meet, making the country susceptible to earthquakes.

In October 2015, a 7.5-magnitude quake in Pakistan and Afghanistan killed almost 400 people across rugged terrain that impeded relief efforts.

The country was also hit by a 7.6-magnitude quake on October 8, 2005, that killed more than 73,000 people and left about 3.5 million homeless, mainly in Pakistan-controlled Kashmir.

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