Prime Minister John Howard has pushed his conservative government as being strong on national security in the run-up to October 9 elections -- an issue all the more pressing after last week's Jakarta embassy bombing.

In announcing the plan, he said oil and gas installations on the north-west shelf were important national assets and needed protecting, although there was no indication of a possible terrorist strike.

The north-west shelf is an oil and gas rich area of the continental shelf in the northern waters of Western Australia state.

"We don't have any information suggesting there is an additional threat to the north-west shelf," Howard said.

"However, because of the critical nature of that facility, the size of it and importance of it to our export income, it is a matter of common sense that we try, where we can, to take additional steps to provide additional security."

Defence Minister Robert Hill said the six million dollar (4.2 million US) trial would involve two vehicles, Northrop Grumman's Global Hawk and General Atomics' Mariner.

"These are state of the art aerial vehicles," Hill told commercial television. "They have 24 to 30 hours sustenance. The issue will be their coverage of the north-west infrastructure and whether we should, from that trial, invest in that capability which could give us a 24 hour a day coverage of that region."

He said the trial would start next year.

The government is officially in caretaker mode ahead of the election, but the Labor opposition said it did not object to the plan.

Howard said the government also planned to buy two more patrol boats to be based in Australia's northwest to boost security and surveillance.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.