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Trump-Putin meeting: John McCain among many to launch blistering attacks on US president's performance at Helsinki summit press conference

Oliver Carroll, Chris Stevenson, Peter Stubley

Donald Trump has caused outrage in Washington after backing Russian President Vladimir Putin's denial that Moscow was involved in meddling in the 2016 US presidential election - over his own nation's intelligence reports

Mr Trump, who was seeking to change the relationship between the White House and the Kremlin, said he could think of "no reason" why Russia would be involved. There is consensus among US intelligence agencies that Russia did seek to alter the election, although Mr Putin has repeatedly denied it.

In Washington, the condemnation came thick and fast. Former CIA director John Brennan called Mr Trump's actions "treasonous", while Republican Senator John McCain called it “one of the most disgraceful performances by an American president in memory.”

The Arizona Republican said the summit with Russian President Vladimir Putin in Helsinki was “a tragic mistake.”

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Outside the Helsinki palace where the meeting took place hundreds of protesters gathered in the streets in support of a variety of causes including abortion rights, gay rights and anti-facism. One sign read: "Lets make human rights great again".

The US president's summit with Mr Putin follows contentious visits to Nato in Brussels and to the UK, where he was greeted with widespread demonstrations against his administration.

Mr Putin meanwhile is on a high after Russia's triumphant hosting of the World Cup, although questions linger over the novichok poisoning of Sergei and Yulia Skripal on British soil.

In an interview on Good Morning Britain before heading off to Helsinki, Mr Trump described his Russian counterpart as a "competitor" and said it was too early to say whether they were friends or enemies.

He also claimed that the EU was one of America's biggest enemies because of "what they do to us in trade" and repeated his description of the media as the "enemy of the people".

Mr Trump went on to issue a tweet blaming "US foolishness and stupidity" and what he called the "rigged witch hunt" for bad relations with Russia, to which the Russian Foreign Ministry replied "We agree".

He had been due to meet alone with the Russian president for one-and-a-half hours from around 11am UK time, but Mr Putin arrived at Helsinki airport half an hour later than expected. The joint press conference was due to start at 2.50pm.

The US president has said he was going into the meeting with "low expectations". There is no official agenda for the talks and Democrats have raised fears that Mr Putin will "try to take advantage", such as by reaching an agreement on the annexation of Crimea.