Sir Keir Starmer has accused the Conservatives of looking to clamp down on opposition voices by trying to find “woke agendas” in British civic institutions.

In his speech at the Civil Society Summit in central London, the Labour leader was critical of Tory attitudes to the likes of the Royal National Lifeboat Institution (RNLI) and the National Trust.

Sir Keir said Rishi Sunak’s Conservatives were “waging a war on the proud spirit of service in this country”.

Promising a “reset” on relations with the charitable sector if he becomes prime minister, he said the governing party seemed set on “sabotaging civil society to save their own skin”.

The Opposition leader said the Tories were engaging in a “kind of weird McCarthyism” – a reference to political repression in the fight against Communism in the US during the mid-20th century – with their response to civic institutions.

In 2019, the RNLI came in for criticism from right-wing figures for its funding of overseas projects to help save people from drowning.

The press coverage led to a huge rise in donations to the volunteer organisation.

Former Brexit Party leader Nigel Farage has previously dubbed the RNLI a “migrant taxi service” for its role in helping asylum seekers in small boats in the English Channel to safety.

The National Trust has also been accused of being “woke” – a modern term for those concerned with looking at how historical racism and injustice should be addressed in the present – for reviewing the influence of slavery on its properties.

Sir Keir said the Government had “got themselves so tangled up in culture wars of their own making” that it had “helped demonise” the RNLI rather than work with it to solve the Channel migrants crisis.

He continued: “Instead of working with the National Trust so more people can learn about – and celebrate – our culture and our history, they’ve managed to demean their work.

“In its desperation to cling on to power at all costs, the Tory Party is undertaking a kind of weird McCarthyism, trying to find woke agendas in the very civic institutions they once regarded with respect.

“Let me tell you, waging a war on the proud spirit of service in this country isn’t leadership. It is desperate, it is divisive, it is damaging.

“It comes to something when the Tories are at war with the National Trust. That is what happens when politics of self-preservation prevail over commitment to service.

“People who are getting on with the things that actually matter – saving lives, supporting those in need, serving others – get caught in the crosshairs of division and distraction.

“So the relationship between government and civil society needs a reset.”

Sir Keir, whose Labour Party is riding high in opinion polls, told the event that a thriving civil society is essential to Labour’s five missions for government, including getting the “economy back on track”.

“We want to harness civil society as one of the three key engines for renewal working alongside the public and private sectors,” he said at the event, which was not open to media questions.

Former prime minister Lord David Cameron “talked about the ‘big society’” more than a decade ago, but “when austerity kicked in we ended up with the ‘poor society’”, the Labour leader added.

Taking questions from “stakeholders” in the audience after his speech on Monday, Sir Keir told the third sector he recognised that charities were “trying to provide support probably with less resource than you’ve ever had before” and said that “has to be addressed as part of what we do going forward”.

But he declined to set out more money for charitable organisations, saying shadow chancellor Rachel Reeves “is not going to let me make budget commitments on stage”.

The Prime Minister claimed Sir Keir’s speech was an attempt to distract from his record as Labour leader.

Mr Sunak told broadcasters he had not seen the speech but “it does sound to me like a distraction from the fact that Keir Starmer, who has been Leader of the Opposition for four years, can’t actually say what he would do differently to run this country”.

Downing Street backed the work of the National Trust and RNLI but stressed that charities needed to operate within the rules.

The Prime Minister’s official spokesman said: “The National Trust is an important institution loved by many and will continue to be.”

He said the Government “pays tribute to the tireless work of the RNLI and its volunteers who save lives at sea”.

More broadly, the spokesman said the Charity Commission had a role in holding organisations to account, ensuring “charities never stray into things like party politics and they avoid inflammatory rhetoric”.

Later in the week, the Labour leader will be touring the country to talk to people about his plan to make Britain’s streets safe.