LONDON -- The UK, US and Australia have announced a historic security pact in the Indo-Pacific, in what's seen as an effort to counter China, BBC reported.

It will let Australia build nuclear-powered submarines for the first time, using technology provided by the US.

The pact, to be known as Aukus, will also cover artificial intelligence, cyber and quantum technologies.

It is the biggest defense partnership among the countries in decades, analysts say.

In recent years, the Western democracies have all expressed concerns about China's growing military assertiveness in the Indo-Pacific.

The new partnership aimed to "promote security and prosperity" in the region, said a joint statement by US President Joe Biden, UK Prime Minister Boris Johnson and his Australian counterpart Scott Morrison.

China's embassy in Washington reacted by saying countries "should not build exclusionary blocs".

It is the biggest security arrangement between the three nations since World War Two, analysts say.

While the US, UK and Australia have long been allies, Aukus formalizes and deepens their defense co-operation.

The pact will focus on military capability, separating it from the Five Eyes intelligence-sharing alliance which also includes New Zealand and Canada.

While Australia's submarines is the big-ticket item, Aukus will also involve sharing of cyber capabilities, AI, quantum and other undersea technologies.

"This is an historic opportunity for the three nations, with like-minded allies and partners, to protect shared values and promote security and prosperity in the Indo-Pacific region," their joint statement read.

The leaders did not refer to China directly, but said regional security challenges had "grown significantly".

China's military build-up and increasing aggression has worried rival powers in recent years.

Beijing has been accused of raising tensions in disputed territories such as the South China Sea.

It has also invested heavily in its Coast Guard in recent years, which analysts say is effectively a de facto military fleet.

Western nations have been wary of China's infrastructure investment on Pacific islands and controversial trade sanctions against countries like Australia.

The US and Australia have referred to this as "economic coercion".