Australia and the US have signed an open-skies agreement, eliminating air travel limits between the two allies that will lead to lower fares.

The accord breaks the long-standing monopoly of the direct route enjoyed by US carrier United Airlines and Australia's Qantas.

Prime Minister Kevin Rudd, visiting in the US, witnessed the signing of the agreement at the US Department of Transport in Washington, and hailed it as a "new era" in trans-Pacific aviation links.

"Its aim is to make it easier and cheaper for even more people to make the air journey across the Pacific to add more strands to our ties," Mr Rudd said.

Even before the pact was signed, Virgin Blue, the Australian low-cost airline partially owned by British tycoon Richard Branson, said that its long-haul international carrier, V Australia, would launch non-stop services between Australia and Los Angeles in December.

V Australia will launch 10 new round-trips from Los Angeles to Australia and "pump almost one-and-a-half billion dollars into LA's economy with the stroke of a pen", US Transportation Secretary Mary Peters said as she signed the agreement with Australia's envoy to Washington, Dennis Richardson.

"Eliminating restrictions on US-Australia air services means lower fares, more convenient service and more opportunity for travellers, commerce and carriers to thrive," she said.

The Sydney-Los Angeles flight corridor is regarded by the Australian Government as a key national asset and Canberra has repeatedly rebuffed Singapore Airlines' decade-long campaign for access to the route.

The US has concluded open-skies agreements with 90 countries and territories.