New Delhi, Sep 17 (PTI) Australia on Friday said its decision to join a historic security pact with the US and UK is aimed at securing the Indo-Pacific and developing capabilities that can contribute along with India and other countries to deter behaviour that threatens peace and security in the region.

The partnership, seen as an effort to counter China in the Indo-Pacific, will allow the US and UK to provide Australia with the technology to develop nuclear-powered submarines for the first time.

Australia's High Commissioner to India Barry O'Farrell said strengthening Australia's defence capabilities through nuclear-powered submarines will form part of the country's contribution to a secure and prosperous Indo-Pacific.

The envoy said the Australian prime minister, the foreign minister and the defence minister spoke to their counterparts in India to inform them of the decision before the announcement on the AUKUS (Australia, the UK and the US) partnership was made.

"The decision reflects a much more challenging strategic environment, an environment we share with India, where great power competition is intensifying, where territorial tensions in the South China Sea, Taiwan and elsewhere are becoming more challenging," he said.

"Indo-Pacific investment in military capability is proceeding at an unprecedented rate and of course that latter point is being driven by China, which has the largest military modernisation programme underway in the world," he told reporters.

O'Farrell said the investment in the Indo-Pacific in developing military capability is proceeding at an "unprecedented rate" and it is being driven by China, which has the largest military modernisation programme underway in the world.

"So strengthening Australia's defence capabilities through nuclear-powered submarines will form part of Australia's contribution to a secure and prosperous Indo-Pacific, and that capability will increase Australia's strategic weight and allow us to more effectively shape our region's future trajectory," he said.

O'Farrell said Australia has taken the decision after deep and serious thought.

"It is in response to those changing strategic circumstances but it's also part of our relationship bilaterally, trilaterally and quadrilaterally across the region," he said.

"These partnerships, including the partnerships that we've announced in relation to submarines with the US and the UK, reinforce existing regional structures, including our shared commitment to ASEAN centrality," he said.

The high commissioner said Australia is striving to retain an inclusive regional order where the rights of all states are respected, whether they are big states or small states.

"We want to contribute to strategic reassurance measures that ensure no one country believes they can advance their strategic ambitions through conflict," he said in a clear reference to China.

"It's not about seeking to provoke any particular regional power, rather it's about ensuring we have capabilities that contribute along with India and other countries to deterring the types of behaviour that threatens the peace and security in the Indo-Pacific today and in the future," O'Farrell said.

The high commissioner said nuclear-powered submarines will provide Australia with the capability it now believes it needs for its defence as they can "travel faster, they can travel for a longer range and they have greater power and endurance".

"The decision reflects a much more challenging strategic environment, an environment we share with India, where great power competition is intensifying, where territorial tensions in the South China Sea, Taiwan and elsewhere are becoming more challenging," he said.

The AUKUS  (Australia, the UK and the US) partnership is also aimed at facilitating sharing of various other critical technologies among the partner countries.

"Through AUKUS, our governments will strengthen the ability of each to support our security and defence interests, building on our longstanding and ongoing bilateral ties," a joint statement issued by US President Joe Biden, Australian Prime Minister Scott Morrison and British PM Boris Johnson said.

It said the three countries will promote deeper information and technology sharing and will significantly deepen cooperation on a range of security and defence capabilities.

"As the first initiative under AUKUS, recognising our common tradition as maritime democracies, we commit to a shared ambition to support Australia in acquiring nuclear-powered submarines for the Royal Australian Navy," it said.   The statement said the development of Australia's nuclear-powered submarines would be a joint endeavour by the three nations, with a focus on interoperability, commonality, and mutual benefit.

France criticised its exclusion from the alliance, saying it reflects a lack of coherence when common challenges are being faced in the Indo-Pacific region.

In its reaction, China criticised the security alliance saying it will gravely undermine regional stability and aggravate the arms race.