20 killed, hundreds injured as quake rattles southern Pakistan

At least 20 people were killed and dozens injured when a shallow earthquake hit southwestern Pakistan in the early hours of Thursday, with rescuers trying to reach coal miners reportedly trapped underground.

Many of the victims died when the roofs and walls of their mud brick houses collapsed after the 5.9 magnitude quake struck Balochistan province in darkness at around three in the morning.

It was felt across at least six cities and towns, but the worst-affected area was the remote mountainous district of Harnai, where landslides triggered by the jolt blocked some roads, hampering rescue efforts.

Authorities are also contending with phone and electricity outages after pylons were damaged.

"We are receiving information that 20 people have been killed due to the earthquake," said Balochistan's home minister Mir Zia ullah Langau, adding that 100 people were injured.

"It is safe to say that hundreds of mud houses were damaged."

A woman and six children were among 20 dead, Suhail Anwar Hashmi, the top government official in Harnai district told AFP, putting the number of injured at around 200.

"There are reports that some 15 coal miners are trapped in a mine on the outskirts of the town due to the quake," he added, saying a rescue team had been dispatched.

It is common in Pakistan for miners to work at night when temperatures are cooler.

Army helicopters were helping to evacuate the injured from remote areas to Quetta, the nearest major city.

Naseer Nasar, the head of Balochistan's Provincial Disaster Management Authority, warned the death toll could rise.

"Our rescue teams have cleared 50 per cent of the roads leading to the Harnai while remaining roads will be cleared in the next two to three hours," Balochistan's home minister Langau added, highlighting the strain rescue teams were under.

The quake caused electricity to fail in the area, with health staff working until dawn without lights in the district's poorly equipped government hospital.

Before daybreak, "we were operating without electricity with the help of torches and mobile flashlights," Zahoor Tarin, a senior official at Harnai hospital, told AFP.

"Most of the injured came with fractured limbs. Dozens of people were sent back after first aid," he said.

The most serious cases were being sent by ambulance to Quetta.

The earthquake was felt in towns throughout Balochistan, which borders Afghanistan and Iran, including provincial capital Quetta, around 170 kilometres (105 miles) west of Harnai.

The US Geological Survey later revised upwards the magnitude of the shallow quake to 5.9.

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

In 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 in 2005 that killed more than 73,000 people and left about 3.5 million homeless, mainly in Pakistan-controlled Kashmir.

A 7.6-magnitude quake in 1935 killed around 30,000 people in Quetta, which at the time was part of British-ruled India.