Britain to deploy 'colossal' warships to test Beijing in South China Sea

British Foreign Secretary Boris Johnson has confirmed the move following a high-level meeting in Sydney with his Australian counterpart Julie Bishop, as well as the Defence Ministers from both nations.

"One of the first things we will do with the two new colossal aircraft carriers that we have just built is send them on a freedom-of-navigation operation to this area to vindicate our belief in the rules-based international system and in the freedom of navigation through those waterways which are absolutely vital for world trade," Johnson said.

On the ABC's 7.30 program, British Defence Secretary Sir Michael Fallon declined to give details of the impending deployment.

"We haven't mapped out the initial deployments yet but, yes, you would expect to see these carriers in the India Pacific Ocean, this part of the world because it is in this part of the world we see increasing tension, increasing challenges," he said.

The United States and close allies, such as Australia and Britain, have long expressed concerns with Beijing's island-building activity and militarisation of one of the busiest commercial sea routes in the world.

Defence Minister Marise Payne has hinted Australia could also play a role alongside Britain in asserting freedom of navigation in the South China Sea.

"Importantly today (Thursday), we also discussed developments in our region, particularly with respect to freedom of navigation and freedom of overflight which is a global issue and countries like Australia and the United Kingdom have a shared interest in those global freedoms," Senator Payne said on Thursday. "We agreed today (Thursday) that we would identify opportunities to conduct, where possible, cooperative activities in the region when we have assets that are in the area at the same time."