One of Australia's key intelligence and security allies has warned of the need for vigilance to "any form of malign intent" from China, as it rapidly seeks to become a global superpower.

Key points: British Defence Secretary Gavin Williamson says Australia shouldn't be blind to China's ambition

British Defence Secretary Gavin Williamson says Australia shouldn't be blind to China's ambition Mr Williamson says Australia will travel through the South China Sea

Mr Williamson says Australia will travel through the South China Sea He says security measures need to be constantly protected

The UK's Secretary of State for Defence Gavin Williamson made the frank comments as he wrapped up a two-day visit to Sydney and Canberra where he met with key military and political figures.

"I think we've always got to be vigilant to any form of malign intent ... Australia [and] Britain see China as a country of great opportunities, but we shouldn't be blind to the ambition that China has and we've got to defend our national security interests," Mr Williamson told the ABC.

"We've got to ensure that any form of malign intent is countered and we see increasing challenges — it's not just from China, it's from Russia, it's from Iran — and we've got to be constantly making sure that our security measures, our critical national infrastructure is protected."

At the conclusion of his first visit to Australia, Mr Williamson said Britain could learn from this country's experience in handling Beijing's attempts to buy influence and to interfere in the political process.

"Certainly I go back to Britain with a lot of lessons learnt as to how you're dealing with some of the challenges that China poses," he said.

"A good example is in terms of what you've been looking at in terms of critical national infrastructure ... we've always encouraged investment from outside but it's making sure it's for right time of investment and it isn't something that puts our utilities, our critical national infrastructure in a more vulnerable position."

Royal Navy to assert navigation rights in South China Sea

The visiting British Defence Secretary has also confirmed a Royal Navy warship will next month sail from Australia through the South China Sea to assert navigation rights in waters claimed by Beijing.

"We've got HMS Sutherland currently approaching Australia and after she's been to Australia, she'll be going through the South China Sea," Mr Williamson told the ABC.

"It's very important that we demonstrate that these are seas as anyone can pass through and we'll be making sure that the Royal Navy will protect those rights for international shipping as she goes to do joint operations with the Japanese, the Koreans and the United States Navy."

He declined to say whether HMS Sutherland would sail within 12 nautical miles of a disputed territory or artificial island claimed by the Chinese as US warships have done, but said it was possible his nation could one day conduct joint patrols with Australia in the disputed waterways.

HMS Sutherland is an anti-submarine warship similar to the design the UK is hoping to build for Australia as part of the $35 billion Future Frigate Program, which is also being contested by Spanish and Italian shipbuilders.