Sir Keir Starmer has said politics should be “less tribal” and suggested he was open to “reasonably-minded people” from other parties joining Labour as he welcomed Tory defector Natalie Elphicke.

Ms Elphicke joined Sir Keir in Dover, her constituency, to launch the Labour Party’s plans to tackle people-smuggling gangs bringing migrants across the Channel in small boats.

Taking questions from the media, he said: “I’m very pleased to welcome Natalie to the Labour Party. You’ve heard the reasons yourself why she took that very difficult step.”

He said he wanted his party to be a place that “reasonably-minded people, whichever way they voted in the past” feel they can join.

“It is an invitation that we should be less tribal in the pursuit of a better country and invite people to our party who want to join in our object of national renewal,” Sir Keir said.

Asked where he would draw the line with right-wing politicians and whether he would welcome Nigel Farage into Labour, he said “a list of names doesn’t help anyone but Nigel Farage wouldn’t want to join Labour”.

He added that he wanted to “bring as many people with us as possible”.

Sir Keir insisted he would need to be ruthless to win the general election as he defended his decision to welcome Ms Elphicke.

Asked whether it was ruthless in an interview with Sky News after his speech, he said: “Yes, I’m ruthless in trying to ensure we have a Labour government who can change this country for the better. Not ruthless for my own ambition, not ruthlessness particularly for the Labour Party. I’m ruthless for the country.

“The only way we’ll bring about a change in this country is if we’re ruthless about winning that general election and putting in place a government of public service, that’ll be a major change in politics.”

Shadow health secretary Wes Streeting had told the Independent he thought Ms Elphicke and Dan Poulter, who left the Tories last month, had “defected with a purpose”, in Dr Poulter’s case because of concern about the NHS, and in Ms Elphicke’s due to the Conservative Party’s immigration policy.

Mr Streeting claimed he has spoken to more Tory MPs considering a move because of the “division and incompetence” of Prime Minister Rishi Sunak’s Government.

Labour MPs have criticised the decision to admit Ms Elphicke to the party, citing her hardline views on immigration and her previous support of her ex-husband after he was found guilty of sexual assaulting two women.

Jess Phillips, the former shadow minister for domestic violence and safeguarding, had earlier said Ms Elphicke should “account for her actions”, adding: “I’m all for forgiveness but I do think that that needs some explaining.”

One Labour MP told the PA news agency they thought the decision was “utterly disgraceful” while another was left in tears by the news.

Asked if he was concerned about the backlash from within the Labour Party to Ms Elphicke’s defection, Sir Keir said on Friday that she had set out the reasons for this “very important and significant” defection.

He said: “It’s a Conservative Party that is on its last legs, it’s out of road, out of ideas, and that is why I genuinely think the mood of the country, and Natalie has picked up on this, is for change and a general election.”

No-one can understand why Mr Sunak is “clinging on by his fingernails” to power, he said.

Ms Elphicke, the MP for Dover, joined Sir Keir to launch Labour’s policy and said a “fresh approach” is needed to halt small boat crossings.

Announcing her decision to switch parties, Ms Elphicke hit out at Mr Sunak’s “tired and chaotic government” and accused him of failing to deliver on his promise to “stop the boats”, adding that Labour would “bring a much better future for our country”.

Downing Street has pointed out her repeated attacks on Labour’s immigration policy while former prime minister Lord Cameron said her defection showed the opposition stood for nothing.