Islamabad - A powerful earthquake rattled Pakistan's south-western Balochistan district on Wednesday, killing at least 21 people and injuring scores of others, media reports said.

The US Geological Survey on its website said a magnitude 6.4 earthquake struck 60 kilometres north-east of Quetta, the capital of Balochistan at 5:10am (2310 GMT).

At least 17 people died in Balochistan's Ziarat district and many were feared trapped under rubble of several houses that collapsed during the strong shocks, DawnNews television channel reported quoting local authorities.

DawnNews said officials in Pishin district also confirmed four deaths.

The earthquake triggered mudslides in several parts of Balochistan and authorities feared that the death toll would rise as the rescue efforts proceed.

Balochistan is Pakistan's largest but most sparsely populated province.

A massive earthquake measuring 7.6 on the Richter scale shook Kashmir and Pakistan's mountain region on October 8, 2005, killing at least 73,000 people and rendering more than 3.5 million others homeless in the harsh winter weather. (dpa)