Sir Keir Starmer should have reassured and explained his immigration policy to a senior Welsh MP rather than telling her “you’re rubbish”, Labour peer Harriet Harman said.

Speaking to Beth Rigby on the Electoral Dysfunction podcast, Harriet Harman criticised the prime minister for telling Plaid Cymru Westminster leader Liz Saville Roberts during PMQs “she talks rubbish” after she called him out for using “island of strangers” in his immigration speech on Monday.

Baroness Harman said: “He should have actually explained ‘look, this is what we’re getting at. We’re it’s a communitarian message, it’s about neighbourliness, it’s about integration’.

“And he should have done that and reassured her and explained rather than just slapping her down.

“I just think to call across the chamber, ‘you’re rubbish’ – I think a prime minister has the opportunity to be a bit more magisterial in that.”

She said she has “been that woman standing there asking the prime minister a heartfelt and serious question, and had the prime minister say, ‘you’re rubbish'”.

Baroness Harman added: “I kind of went ‘ouch’ at that point, because I’ve been in that situation myself.

“I think people do want an explanation and he’s got an explanation and he should have done that rather than hit at the messenger.”

After Sir Keir used the phrase “island of strangers” while announcing a crackdown on immigration, fellow Labour MPs, businesses and industry reacted angrily.

The rhetoric was likened by some critics to Enoch Powell’s rivers of blood speech.

Ahead of PMQs on Wednesday, Cabinet Office minister Pat McFadden tried to move the debate away from Sir Keir’s controversial remarks.

“I think we should focus on the policy,” he told Sky News.

“Immigration has contributed a huge amount to the UK, it will in the future, I think the public want a sense of rules around it, that is what the prime minister was speaking about.”

He said the row was “overblown” and he might use the “island of strangers” phrase “depending on the context”.