More than six million people watched the first live leaders' debate between Boris Johnson and Jeremy Corbyn.
The pair's appearance on ITV drew an average audience of 6.7m viewers when it aired between 8pm and 9pm yesterday, according to overnight ratings.
The programme peaked at 7.3m, ITV said.
According to one report, the programme peaked at seven million viewers between 8.50pm and 8.55pm.
ITV said that Johnson v Corbyn: The ITV Debate, hosted by newsreader Julie Etchingham, was watched by a peak of 1.1m 16-34 year olds.
The leader of the Conservatives clashed with the Labour leader over their rival plans for Brexit during the heated debate, with Mr Corbyn describing the Prime Minister's pledge to "get Brexit done" by the end of January as "nonsense", while Mr Johnson suggested his rival was "not fit to lead our country".
Mr Johnson and Mr Corbyn also contested issues concerning the NHS and a further referendum on Scottish independence in the first televised debate of the General Election campaign.
There are further leaders' events planned ahead of the election, with the BBC hosting a Question Time special on Friday.
But the Tories have come under fire after rebranding one of their official Twitter accounts as a fact-checking service during the debate.
Twitter issued a sharp rebuke that "any further attempts to mislead people" would result in "decisive corrective action" after the party's verified press office account was temporarily renamed "factcheckUK".
The Electoral Commission - the official elections watchdog - also issued a warning saying voters were entitled to expect "transparency and integrity" from campaigners.
Senior party figures brushed off the controversy, saying it was part of their "instant rebuttal" mechanism to challenge "nonsense" claims made by Mr Corbyn during the debate that they were preparing to sell off the NHS.
However opposition parties accused the Tories of adopting the tactics of Donald Trump or Vladimir Putin to deliberately mislead the public.
The row coincided with an appeal from the Archbishops of Canterbury and York to campaigners in the election to "honour the gift of truth".
In a statement, Twitter said: "Twitter is committed to facilitating healthy debate throughout the UK general election.
"We have global rules in place that prohibit behaviour that can mislead people, including those with verified accounts.
"Any further attempts to mislead people by editing verified profile information - in a manner seen during the UK election debate - will result in decisive corrective action."
An Electoral Commission spokesman said: "While we do not have a role in regulating election campaign content, we repeat our call to all campaigners to undertake their vital role responsibly and to support campaigning transparency."
Foreign Secretary Dominic Raab insisted it had been perfectly clear throughout that it was a Conservative Party account and that no one among voters "gives a toss" about the cut and thrust of social media.
"It was pegged to the CCHQ account. No one who looked at it for more than a split second would have been fooled," he told BBC Breakfast.
"I knock on doors every day. No one gives a toss about the social media cut and thrust. What they care about is the substance of the issues.
"Of course there is huge amounts of scepticism about the claims of all the politicians. What we are not going to do is have this nonsense put around by Labour."
However shadow equalities secretary Dawn Butler said the account should have been suspended by Twitter once they became aware of what happened.
She told the BBC Radio 4 Today programme: "They could have just suspended the account and taken it down and, to me, that would have been the better punishment."
Liberal Democrat Brexit spokesman Tom Brake said: "This is straight out of Donald Trump or Putin's playbook.
"Not content with excluding the voice of Remain from this debate, the Tories are now resorting to deliberately misleading the public.
"People know they can't trust a word that Boris Johnson or the Conservatives say."
The row comes amid repeated accusations that Mr Johnson struggles to tell the truth.
The Prime Minister was met with derisive laughter from the studio audience in Salford when he said that he considered the truth was "very important" in the General Election.
A snap YouGov poll following the debate suggested Mr Johnson came out narrowly ahead - with 51 per cent saying they thought he had won, against 49 per cent for Mr Corbyn.
However, on the issue of trust it was the Labour leader who came out on top, with 45 per cent saying he was the more trustworthy, against 40 per cent for the Prime Minister.
The Conservatives have previously faced criticism for "doctoring" a TV clip of shadow Brexit secretary Sir Keir Starmer to make it appear that he had been stumped by a question on the party's policy on the EU.
Meanwhile the Archbishop of Canterbury, the Most Rev Justin Welby, and the Archbishop of York, Dr John Sentamu, have issued an appeal to all those involved in the election to "speak accurately" and to engage "responsibly" on social media.
In a joint pastoral letter to the Church of England, they said: "As followers of Jesus Christ each of us is called to honour the gift of truth, both to speak it and to seek it.
"We all have a responsibility to speak accurately, to challenge falsehoods when we hear them, and to be careful to separate facts from opinion."