QUETTA: Suspected tribal militants blew up two major natural gas pipelines in Pakistan's southwest on Tuesday, forcing the suspension of supplies to the strategic region bordering Afghanistan and Iran, officials said.

"We have suspended gas supply to the province as the pipelines are on fire," Inayatullah Ismail, a spokesman for Sui Southern Gas Company (SSGC) that supplies gas to the southern parts of the country told Reuters.

Thin-populated Baluchistan is home to Pakistan's largest gas supplies as well as one of the largest copper deposits in the world, with estimated ore reserves of 412 million tonnes. Pakistan's third port, built with Chinese help, is at Gawadar in Baluchistan.

Ismail said he was unsure how long it would take to extinguish the fire and resume gas supplies.

The twin explosion followed a late Monday night attack on four transmission pylons in the Bolan area, suspending power supplies to around half of the province's 30 districts.

A spokesman for the government-owned power company said that electricity to some parts of the provincial capital of Quetta had been restored, but the rest of the districts had been "in complete darkness for the last 24 hours".

The separatist Baluch Liberation Army called media offices in Quetta, saying it had blown up the pylons and threatening to stage further attacks.