Trump says he has been 'tougher on Russia than anybody'

US President Donald Trump and Britain's Prime Minister Theresa May held a meeting on Friday at Chequers, the prime minister's country residence, near Ellesborough, northwest of London

US President Donald Trump on Friday said he had been "tougher on Russia than anybody", ahead of a summit with his Russian counterpart Vladimir Putin on Monday.

"We have been far tougher on Russia than anybody... We have been extremely tough on Russia," he said at a joint press conference with British Prime Minister Theresa May.

He recalled that 60 intelligence officers were expelled from the Russian embassy in Washington in response to a nerve agent attack on a former Russian spy in Britain.

Russia has denied any involvement in the attack.

"We have been very strong on Russia," Trump told reporters at the British premier's Chequers country residence, after talks with May.

Trump's campaign and transition team have been accused of colluding with Russian agents in an effort to influence the 2016 US election against Hillary Clinton.

The US president is due to meet Putin in Helsinki for talks in which he hopes to establish a good personal relationship with his Russian counterpart.

US-Russian relations have suffered from years of disagreement over the Syrian conflict, Russia's annexation of Crimea and its involvement in eastern Ukraine.

"I'm not going in with high expectations but we may come out with very surprising things," Trump said.

The president said he wanted to develop a relationship with Putin, which he said would be "good for Russia, good for everybody".

Trump claimed he would be going into the meeting with Putin with NATO better financed, more united and resolute.

The US president said he would be discussing Syria, the Middle East, Ukraine and nuclear proliferation.

"That would be a tremendous achievement if we could do something on nuclear proliferation," he said.

Trump said he did not think Russia would have invaded Crimea if he had been in the White House at the time.

Referring to an ongoing investigation into ties between his election campaign and Russia, he decried a "rigged witch-hunt" that was hurting the United States and its relationship with Russia.

May said the most important thing was that Trump would be going into the meeting with Putin with the 29-strong NATO military alliance united behind him.

"We agree that it is important to engage Russia from a position of strength and unity and that we should continue to deter and counter all efforts to undermine our democracies," she said.

Trump also slammed the Nord Stream II pipeline that is set to bring gas from Russia to Germany, calling it a "horrible mistake" that would give Moscow power over Berlin.

"It's a horrific thing being done where you're feeding billions and billions of dollars from Germany... into the coffers of Russia when we're trying to do something so that we have peace in the world."

US President Donald Trump and Britain's Prime Minister Theresa May held a meeting on Friday at Chequers, the prime minister's country residence, near Ellesborough, northwest of London