SYDNEY • US and Australian troops plan to step up training so that they are "fully prepared" to answer challenges in the Pacific, United States Vice-President Joe Biden said yesterday amid rising tensions over Beijing's claims in the South China Sea.

Speaking in Sydney after meeting Prime Minister Malcolm Turnbull, Mr Biden said the two nations were a "genuine brotherhood" committed to "making sure the sea lanes are open and the skies are free for navigation".

"They are the lifelines of commerce and economic growth worldwide," Mr Biden said in the wake of last week's ruling by a UN-backed tribunal against Beijing's claims in the disputed waters.

Beijing asserts sovereignty over almost all of the South China Sea, despite rival claims from its South-east Asian neighbours - most notably US ally the Philippines, which took the case to the Hague-based Permanent Court of Arbitration.

The US, like Australia, has no claims in the South China Sea, but insists that all shipping has a right to pass through what it regards as international waters.

"We also discussed the steps that Australia and the United States are taking so our troops can train more together and increase our interoperability so we are fully prepared to respond to any challenges in the Pacific with a united front," Mr Biden said.

"It's important we stand together," he added, as he stressed that the US was a Pacific power and intended to remain so.

Mr Turnbull used a short media briefing alongside Mr Biden to announce that Australia was expanding its role in Iraq to include the training of law enforcement officers as well as its current training of the Iraqi army.

Australia has been a staunch ally of the US in Iraq and in the fight against the Islamic State in Iraq and Syria (ISIS).

Mr Biden's visit, which comes as President Barack Obama enters the final months of his administration, ends today when he travels to New Zealand.

AGENCE FRANCE-PRESSE