The Federal Government is buying a fleet of surveillance drones for border security and other duties, creating around 100 jobs for an estimated cost of $3 billion.

Prime Minister Tony Abbott announced the upcoming purchases while touring South Australia ahead of the state’s election.

Mr Abbott said the unmanned aerial vehicles (UAV) will be used to patrol Australia’s borders for potentially illegal entries and to monitor important energy infrastructure.

“Given that Australia has responsibility for something like 11 per cent of the world's oceans, it's very important that we've got a very effective maritime surveillance capability,” the Prime Minister said in an address at Adelaide's Edinburgh air force base.

“These Tritons are an unarmed, unmanned aerial vehicle but they're excellent for maritime surveillance because they can stay in the air for about 24 hours and their range is something like 15,000 kilometres so they're an extraordinarily capable aircraft.”

The Prime Minister has not said how many drones the government will buy, or how much it will cost, but an ABC report in 2012 said the Defence Force had its eye on seven of the Triton units.

Mr Abbott also detailed a $78 million maintenance contract for the air force's Wedgetail early warning aircraft, to be carried out by BAE Systems Australia in Adelaide.

The Prime Minister said it was an obvious choice.

“Obviously this is money that will be spent in and around Adelaide and that's good news for employment in a city that's had some bad news on employment lately,” he said.

“It's obviously a good outcome for the about 300 industry staff who are employed in the Wedgetail project around the country including in Adelaide.”

SA Defence Industries Minister Jack Snelling welcomed the drones, but said he wanted money for ship-building too.

“The last Air Warfare Destroyer will roll off the line imminently and the [ship-building] workforce there is due to peak very, very soon,” he said.

“What we need is to know what's going to replace it because the future submarine project and the viability of that is critical to there being an ongoing naval shipbuilding presence there at Osborne.”