Republican Donald Trump's plan to deport 11 million undocumented immigrants from the US has been savaged by his party rivals in a TV debate.

Two others also running for the Republican presidential nomination, John Kasich and Jeb Bush, said the plan was both impractical and divisive.

Trump, a billionaire New Yorker who has been leading in the polls, was booed as he tried to counter-attack.

Another source of friction at the debate in Milwaukee was foreign policy.

The eight candidates were divided on whether the US should do more to intervene in the Middle East, especially in the fight against Islamic State militants.

But immigration sparked the biggest confrontation, when Mr Trump said a wall should be built at the US-Mexico border and all migrants living illegally in the US must be deported.

This was met with disdain by Kasich, the governor of Ohio.

"Come on, folks, we all know you can't pick them up and ship them back across the border. It's a silly argument. It's not an adult argument."

Bush, the former Florida governor, said it would tear families apart and played into the hands of Democratic front-runner Hillary Clinton.

(BBC)