The President criticised Keir Starmer's rhetoric on Russia, claiming the former British prime minister was 'too tough' and 'too nasty' towards Vladimir Putin.

Mr Trump made the extraordinary remarks while sitting next to Ukrainian president Volodymyr Zelensky during a bilateral meeting on Tuesday.

Playing down the possibility of a direct confrontation between the UK – a staunch ally of Ukraine – and Russia, Mr Trump said: 'I think you'll be OK. But I'll say the rhetoric from your last prime minister was too tough. I've seen that dialogue and it's too nasty.'

The President added that the UK government 'needs to be a little bit careful' in its approach to Russia.

Asked about current Prime Minister Andy Burnham's stance on Russia, Mr Trump said: 'I haven't heard the rhetoric, but I think he's going to be good.'

Mr Trump also took a stern tone towards Putin, telling him to 'settle this war' with Ukraine.

However the US President dealt a blow to Ukraine after he failed to confirm he would apply economic sanctions against Russia which have been approved by Congress.

Mr Trump's blast at Putin came as he arrived at United Nations headquarters in New York where, after addressing delegates, he met Mr Zelensky.

During his address to the UN General Assembly, President Trump said: 'Last week, in honour of Senator Lindsey Graham, I signed a powerful new law passed by Congress, providing me with enormous new tariff authorities.

'And, if necessary, I will have to use them. It's time to stop the killing.'

Lindsey Graham was the US senator for South Carolina and a staunch ally of Ukraine before his death in July.

Since returning to office Mr Trump has repeatedly expressed confidence that the US will be able to broker an end to the war, only for the conflict to continue with thousands more lives being lost.

He promised the same outcome again on Tuesday, saying: 'We're working very closely with the leaders of Russia and Ukraine and we will get that one done.'

It came after Mr Trump signed a much-anticipated Russia and Iran Sanctions Bill into law last week.

The Act allows the White House to impose tariffs on goods imported from countries that purchase Russian energy products and also authorises sanctions against parties supporting its invasion of Ukraine, including the country's financial sector. 

Ukraine has been urging the US to step up its sanctions against Russia for years but the Act, championed by Senator Graham, had been delayed repeatedly in Congress.

Despite signing the Sanctions Bill into law, Mr Trump continued to push both sides towards the negotiating table. 

In a meeting with Mr Zelensky, Mr Trump repeated that he thought the two countries in the war would 'make a deal'. 

He said: 'We talk about it [a deal] a lot, including with President Putin, and I think something is going to happen. Certainly, they [the Ukrainians] are very good fighters.

'They can be proud of themselves, whatever happens. We'll see what happens. Very capable people and very capable leadership.'

However Mr Trump repeated his claim that Ukraine's air strikes on Russian oil refineries were causing higher fuel prices worldwide.

He added: 'The diesel oil, the diesel fuel, has gone up quite a bit. We'll be talking about that. The President [Zelensky] and I are trying to figure out a solution.

'I think it [a deal] is going to happen. We have a lot to talk about. The relationship is very strong and with Europe it is very strong.'

That message was echoed by French president Emmanuel Macron, who urged Russia and Ukraine to halt strikes on energy and civilian targets, and resist what he called the 'law of the jungle'.

Mr Zelensky thanked Mr Trump for his support saying: 'I hope we will end this war and President Trump will help us. I think we need to do this as quickly as possible, before winter.'