GLASGOW - China and Russia hit back at United States President Joe Biden on Wednesday (Nov 3) after he accused both nations of failing to show leadership at vital United Nations climate talks in Scotland.

Mr Biden, who joined more than 100 world leaders at COP26, on Tuesday criticised Chinese President Xi Jinping and Russian leader Vladimir Putin for not attending the summit.

"Actions speak louder than words," Chinese Foreign Ministry spokesman Wang Wenbin responded on Wednesday. "What we need in order to deal with climate change is concrete action rather than empty words."

He added: "China's actions in response to climate change are real."

The clash of superpowers risks undermining the COP26 conference in Glasgow, which hopes to end in a global deal to limit the threat from climate warming and speed up the transition to greener and cleaner economies.

Cooperation from all three nations is vital for any breakthrough at the conference, one of the most important climate gatherings in years.

China is the world's leading greenhouse gas polluter, followed by the US, India and Russia.

Mr Xi issued a written statement to the conference on Tuesday, but offered no new steps to deepen emissions cuts.

"The fact that China is trying to assert, understandably, a new role in the world as a world leader - not showing up, come on," Mr Biden told a news conference in Glasgow.

"It just is a gigantic issue and they walked away. How do you do that and claim to be able to have any leadership?" Mr Biden said, adding that the same was true for Mr Putin.

"It's been a big mistake, quite frankly, for China not showing up. The rest of the world looked at China and said 'What value are they providing?'"

Responding to the accusation, Kremlin spokesman Dmitry Peskov said: "We disagree.

"We are certainly not minimising the importance of the event in Glasgow, but Russia's actions are consistent and thoughtful and serious."

On Tuesday, China's top climate envoy defended Beijing's efforts to fight climate change, calling its plans ambitious.

Mr Xie Zhenhua said Beijing's updated national climate plans, or Nationally Determined Contribution (NDC), ensured China would progressively reduce its reliance on coal and continue to ramp up investment in renewable energy to meet the nation's huge appetite for electricity.

China is the world's top coal consumer and producer, but also by far the planet's leading investor in renewable energy. In a separate new statement on Wednesday, it said it is targeting a 1.8 per cent reduction in average coal use for electricity generation at power plants over the next five years, in a bid to lower greenhouse gas emissions.

Beijing recently firmed up the language of its NDC submitted to the UN as part of the UN Paris climate agreement process.

"Our NDC is that we need to achieve CO2 emissions peaking before 2030 and achieve carbon neutrality before 2060. That's a huge difference from 'around' or 'by'. I think it is already ambitious," Mr Xie told a press briefing in Glasgow.

Mr Xie also took a swipe at former US president Donald Trump, who quit the 2015 Paris climate agreement, a pact that was achieved in part by US-China cooperation under former president Barack Obama.

"China-US joint efforts resulted in the Paris Agreement... it was hard-fought, you can't just give up, but the US gave up. Five years were wasted, but now we need to work harder and catch up."

Mr Xie said China's green energy revolution was powering ahead. The nation's installed renewable energy capacity was now 890 gigawatts (GW), accounting for 32 per cent of the world's total. The goal is for 1,200GW of installed green energy by 2030.

But he also said China will likely need to build more coal-fired power stations to help meet energy needs, putting the nation at odds with global calls to end all coal-fired power investments.

"In some cases we may need to build some new coal-power plants to ensure the safety and stability of our power grid. But those newly built coal-fired power plants, they will all apply the highest possible standard in terms of technology, emissions and energy consumption," Mr Xie told the briefing.