Western Power, AlintaGas and the Water Corporation were contacted by the Attorney General's office and WA Police State Security after warnings from US officials that Australia, along with five other countries would be targeted by terrorists.

Electricity, gas, oil and water utilities have increased security and police were told to patrol sites.

A Western Power spokesman said all of WA power stations were alerted. "We're continuing operations as usual with the same heightened level of vigilance imposed after September 11," he said.

Epic Energy, which owns the high-pressure Dampier-to-Bunbury natural gas pipeline, said its security measures were suitable for the circumstances. "The latest threats are a reminder to stay on our toes and not get complacent," said maintenance manager, Tim Clarey.

Energy giant Woodside Petroleum last week awarded a $7.5 million, three-year contract to Group 4 Securitas to monitor most of its onshore and North West Shelf oil and gas facilities.

A Woodside spokesman said the company had high security levels, which were reviewed after September 11 and again after the latest threat.