Russia's foreign minister on Sunday accused the United States of driving increased militarisation in Southeast Asia, saying that Washington was trying to contain Beijing and Moscow's influence in the region.

Sergei Lavrov was speaking to reporters at Phnom Penh's airport after attending the East Asia Summit in Cambodia -- and before flying to Bali for the G20 summit where China's leader Xi Jinping and US President Joe Biden will meet.

Earlier on Sunday, Biden said he would establish "red lines" with Xi.

Washington is attempting to boost its influence in Southeast Asia, worried by Beijing's increasingly assertive behaviour in the region, which it views as its strategic backyard.

Lavrov accused the United States of pushing the "militarisation of this region, clearly aimed at containing China and limiting Russian interests in the region".

As the Ukraine invasion has ground on, and with Western sanctions biting, Russia has pivoted toward Southeast Asia in an attempt to shore up its battered economy.

Lavrov called Washington's strategy -- which has seen the United States push for closer relations with Southeast Asian nations -- "not inclusive and that compete with the inclusive structures created around ASEAN".

The regional summit in Cambodia has been dominated by international concerns, as first Ukraine and then the US-China rivalry overshadowed local concerns such as Myanmar.

AFP