British foreign policy is contributing to the likelihood of terrorism within the country, Labour leader Jeremy Corbyn will say.

In his first major speech since the Manchester terror attack, Corbyn will say that the "war on terror" has failed and that smarter ways of tackling extremism must be found.

At the speech in London on Friday (26 May), Corbyn will say: "We must be brave enough to admit the 'war on terror' is simply not working. We need a smarter way to reduce the threat from countries that nurture terrorists and generate terrorism.

"Many experts, including professionals in our intelligence and security services, have pointed to the connections between wars our government has supported or fought in other countries and terrorism here at home."

He will add: "That assessment in no way reduces the guilt of those who attack our children. Those terrorists will forever be reviled and held to account for their actions."

Corbyn will also criticise the Conservatives for cutting police numbers by 20,000 since 2010.

It comes as 5,000 British troops were deployed across "sensitive" security locations across the country in the wake of Monday's terror attack.

The move was criticised by the head of the Police Federation, Steve White, who said it only demonstrated how much police budget cuts have affected the ability to deliver a good service.

"As welcome as [British troop deployment] is, we cannot avoid the reasons it is needed at all," White said.

"There is no ignoring the fact that we, the police, simply do not have the resources to manage an event like this on our own."

Labour leader Jeremy Corbyn delivers a campaign speech in London on 29 April. Getty

Corbyn has pledged to reinvest into policing if a Labour government was to be elected on 8 June.

"Labour will reverse the cuts to our emergency services and police," Corbyn will say. "Once again in Manchester, they have proved to be the best of us.

"Austerity has to stop at the A&E ward and at the police station door. We cannot be protected and cared for on the cheap.

"There will be more police on the streets under a Labour Government. And if the security services need more resources to keep track of those who wish to murder and maim, then they should get them."

He will add: "No government can prevent every terrorist attack. If an individual is determined enough and callous enough sometimes they will get through.

"But the responsibility of government is to minimise that chance – to ensure the police have the resources they need, that our foreign policy reduces rather than increases the threat to this country and that at home we never surrender the freedoms we have won and that terrorists are so determined to take away."

Meanwhile a YouGov poll for the Times has put Labour at 38% of the vote only five points behind the Conservatives, the smallest margin between the parties since Theresa May became prime minister.