Britain Wednesday hit back at critics including the UN refugee agency and football presenter Gary Lineker, after he compared its new plan on illegal immigration to the rhetoric of Nazi-era Germany.

The Conservative government intends to outlaw asylum claims by all illegal arrivals and transfer them elsewhere, such as Rwanda, in a bid to stop thousands of migrants from crossing the Channel on small boats.

Rights groups including the United Nations High Commissioner for Refugees said the plan would make Britain itself an international outlaw under European and UN conventions on asylum.

Presenting the draft legislation to parliament, Home Secretary Suella Braverman attached a letter to lawmakers conceding that she could not confirm yet whether the plan respected European human rights law.

But in a round of broadcast interviews, the interior minister insisted the government was within its rights to stop the seaborne migrants, who she said could exceed 80,000 this year.

"We're not breaking the law," she told Sky News, claiming support from the "vast majority" of the British public.

"We are very confident that our measures that we've announced yesterday (Tuesday) are in compliance with our international law obligations."

- 'Immeasurably cruel' -

Lineker, a former striker who presents the BBC's flagship football coverage on TV, was warned by the broadcaster to respect its social media guidelines after he lashed out at Braverman on Twitter.

"Good heavens, this is beyond awful," he tweeted over a video of Braverman explaining her plan, in the latest of a series of broadsides against the Conservatives.

"There is no huge influx. We take far fewer refugees than other major European countries," Lineker noted.

"This is just an immeasurably cruel policy directed at the most vulnerable people in language that is not dissimilar to that used by Germany in the 30s, and I'm out of order?"

Braverman has often been accused herself of using inflammatory language over the migration issue, as the Conservatives try to restore their weak standing in opinion polls ahead of local elections in May.

"I'm obviously disappointed that he should attempt to equate our measures with 1930s Germany. I don't think that's an appropriate way of framing the debate," she told BBC radio.

"My role as home secretary, is first and foremost, to be honest with the British people and to the British people," the right-wing hardliner added.

"And if that makes some people feel uncomfortable, then you know that we can have a debate about the substance of the measures."