Rishi Sunak has defended the controversial voter ID policy as "entirely reasonable" - despite thousands of people in England being turned away from polling stations.
It comes just days after the ex-Cabinet minister Jacob Rees-Mogg appeared to describe the law as an attempt at gerrymandering that backfired to suppress the Tory vote.
May's local elections in which the Tories suffered heavy defeats - losing in excess of 1,000 councillors - was the first time the law applied across England.
Speaking earlier this week the Mayor of London Sadiq Khan also urged ministers to suspend the system before it is used for the first time in a general election - likely in 2024.
He said there was "no evidence" of widespread offences of voter impersonation at the ballot box, claiming: "I think this is a deliberate Conservative tactic to suppress the vote."
But speaking facing questions in Japan, the Prime Minister attempted to defend the policy and made clear he was "very comfortable" with the Government's approach.
Mr Sunak said "tonnes of other countries" in Europe already have the law while the rules have been in place in Northern Ireland since 2003.
He added: "Those are all facts that make me think it is an entirely reasonable thing to do in line with lots of countries including Northern Ireland, which the Labour government did.
"Also I think it is an entirely reasonable thing that there is integrity in our voting system. That's my general view on that".
The PM said the Electoral Commission, which admitted this month some voters had been turned away from polling stations, will evaluate and publish findings on May's elections.
He said: "But in general I'm very comfortable about the approach that we've taken".
There is no final tally of the number of voters who were turned away for not having the correct form of ID at the May elections. But initial reports have raised fears that many thousands could have been.
Data compiled by the BBC shows out of 435,000 voters in Yorkshire and Lincolnshire, 4,348 were turned away and 1,611 of them did not return to the ballot box later.
In Bradford alone, 1,261 people were turned away, the figures add.
The PM also said that the Government's position has not changed in regards to giving 16 and 17-year-olds the right to vote and EU citizens who have lived in the UK for decades.
He said: "I think that voting is a privilege. We need a set of rules in place about who is eligible to vote. And we have no plans to change that."
