Jeremy Corbyn has taken the hugely controversial step of blaming Britain’s foreign wars for terror attacks such as the Manchester suicide bombing.

The Labour leader claimed a link between “wars our government has supported or fought in other countries and terrorism here at home”, as he relaunched his party’s election campaign on Friday after the three-day pause.

Mr Corbyn stressed that his assessment is shared by the intelligence and security services and “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,” he said.

But, vowing to “change what we do abroad”, he added: “An informed understanding of the causes of terrorism is an essential part of an effective response that will protect the security of our people, that fights rather than fuels terrorism.

“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.”

In the speech, the Labour leader also linked the Manchester atrocity to Theresa May’s failure to ensure “the police have the resources they need”.

“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,” he said.

“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 continued: “No government can prevent every terrorist attack. If an individual is determined enough and callous enough sometimes they will get through.”

But it is Mr Corbyn’s determination to link the 22 deaths in Manchester with Britain’s involvement in the war on terror that is certain to trigger a backlash.

Manchester terror attack: What we know so far

In the speech, he did not name any specific wars, having – as a backbencher – opposed the conflicts in Afghanistan, Iraq, Libya and against Isis, in Iraq and Syria.

At the Iraq Inquiry in 2010, Baroness Manningham-Buller, the former head of MI5, said the invasion had “substantially” increased the terrorist threat to the UK, by radicalising young people.

Mr Corbyn was one of just 13 MPs to oppose David Cameron and vote against the Libya bombing in March 2011.

After the overthrow of Muammar Gaddafi, Libya descended into bloody chaos, with two rival governments and the growing menace of jihadi extremism.

Libyans in the UK, including in Manchester, have spoken of their fear that the growing Islamist radicalisation in their home country was also taking root among refugees who moved here.

And intelligence briefings have suggested Salman Abedi, the Manchester suicide bomber, moved to Libya, before returning to Britain as recently as last week.

Manchester explosion in pictures Show all 37 1 /37 Manchester explosion in pictures Manchester explosion in pictures People running down stairs as they attempt to exit the Manchester Arena after a blast, where U.S. singer Ariana Grande had been performing, in Manchester Twitter/@ZACH_BRUCE/ via REUTERS Manchester explosion in pictures Helpers attend to people inside the Manchester Arena after a suspected suicide bomber detonated an explosive device at the end of an Ariana Grande concert, killing 22 people PA wire Manchester explosion in pictures Armed officers guard outside a hotel near the Manchester Arena following reports of an explosion, in Manchester, Britain EPA Manchester explosion in pictures Police officers are seen outside the Manchester Arena, where U.S. singer Ariana Grande had been performing, in Manchester, northern England Reuters Manchester explosion in pictures MANCHESTER, ENGLAND - MAY 23: Police escort members of the public from the Manchester Arena on May 23, 2017 in Manchester, England. An explosion occurred at Manchester Arena as concert goers were leaving the venue after Ariana Grande had performed. Greater Manchester Police have confirmed 19 fatalities and at least 50 injured. (Photo by Christopher Furlong/Getty Images) Getty Images Manchester explosion in pictures MANCHESTER, ENGLAND - Emergency services arrive close to the Manchester Arena on May 23, 2017 in Manchester, England. There have been reports of explosions at Manchester Arena where Ariana Grande had performed this evening. Greater Manchester Police have have confirmed there are fatalities and warned people to stay away from the area. (Photo by Dave Thompson/Getty Images) Getty Images Manchester explosion in pictures MANCHESTER, ENGLAND - MAY 23: Police escort members of the public from the Manchester Arena on May 23, 2017 in Manchester, England. An explosion occurred at Manchester Arena as concert goers were leaving the venue after Ariana Grande had performed. Greater Manchester Police have confirmed 19 fatalities and at least 50 injured. (Photo by Christopher Furlong/Getty Images) Getty Images Manchester explosion in pictures Medics deploy at the scene of a reported explosion during a concert in Manchester, England on May 23, 2017. British police said early May 23 there were "a number of confirmed fatalities" after reports of at least one explosion during a pop concert by US singer Ariana Grande. Ambulances were seen rushing to the Manchester Arena venue and police added in a statement that people should avoid the area / AFP PHOTO / Paul ELLIS (Photo credit should read PAUL ELLIS/AFP/Getty Images) AFP/Getty Images Manchester explosion in pictures Police and fans close to the Manchester Arena, after reports of an explosion Getty Images Manchester explosion in pictures There have been reports of explosions at Manchester Arena where Ariana Grande had performed Getty Images Manchester explosion in pictures Police deploy at scene of explosion in Manchester, England, at a concert in Manchester Arena AFP/Getty Images Manchester explosion in pictures Police stand by a cordoned off street close to the Manchester Arena Getty Images Manchester explosion in pictures Police deploy at scene of explosion in Manchester, England AFP/Getty Images Manchester explosion in pictures Police deploy at scene of a reported explosion during a concert in Manchester, England, on May 23, 2017. British police said early May 23 there were "a number of confirmed fatalities" after reports of at least one explosion during a pop concert by US singer Ariana Grande. Ambulances were seen rushing to the Manchester Arena venue and police added in a statement that people should avoid the area AFP/Getty Images Manchester explosion in pictures An ambulance drives away from the Manchester Arena, where U.S. singer Ariana Grande had been performing, in Manchester Reuters Manchester explosion in pictures Police escort members of the public from the Manchester Arena in Manchester, England. Getty Images Manchester explosion in pictures A woman sits in the street in a blanket near the Manchester Arena as police guard the area following reports of an explosion, in Manchester, Britain EPA Manchester explosion in pictures Two women wrapped in thermal blankets stand near the Manchester Arena, where US singer Ariana Grande had been performing, in Manchester Reuters Manchester explosion in pictures A Royal Logistic Corps (RLC) bomb disposal robot is unloaded outside the Manchester Arena following reports of an explosion, in Manchester. At least 19 people have been confirmed dead and others 50 were injured, authorities said. It is being treated as a terrorist incident until police know otherwise EPA Manchester explosion in pictures A Royal Logistic Corps (RLC) bomb disposal robot is unloaded outside the Manchester Arena following reports of an explosion, in Manchester EPA Manchester explosion in pictures Members of the public receive treatment from emergency service staff at Victoria Railway Station close to the Manchester Arena on May 23, 2017 in Manchester, England. There have been reports of explosions at Manchester Arena where Ariana Grande had performed this evening. Greater Manchester Police have have confirmed there are fatalities and warned people to stay away from the area Getty Images Manchester explosion in pictures Armed police after a suspected terrorist attack at the Manchester Arena at the end of a concert by US star Ariana Grande left 19 dead PA wire Manchester explosion in pictures Emergency services arrive close to the Manchester Arena in Manchester Getty Images Manchester explosion in pictures An amoured police vehicle patrols near Manchester Arena in Manchester Getty Images Manchester explosion in pictures A man carries a young girl on his shoulders near Victoria station in Manchester AFP/Getty Images Manchester explosion in pictures Police officers stand at the Miller Street and Corporation Street Crossroads, in front of the Manchester Arena in Manchester, England Getty Images Manchester explosion in pictures Police block a road near to the Manchester Arena in central Manchester, England AP Manchester explosion in pictures Armed police patrol near Victoria station in Manchester, northwest England. Twenty two people have been killed and dozens injured after a suspected suicide bomber targeted fans leaving a concert of US singer Ariana Grande in Manchester Getty Images Manchester explosion in pictures Police forensic officers leave the Manchester Arena as they investigate the scene of an explosion in Manchester Getty Images Manchester explosion in pictures A forensic officer collects evidence on a walkway between Victoria station and Manchester Arena following a deadly terror attack in Manchester, Getty Images Manchester explosion in pictures A woman and a young girl wearing a t-shirt of US singer Ariana Grande talks to police near Manchester Arena following a deadly terror attack in Manchester, Getty Manchester explosion in pictures epaselect epa05982725 Susan Walton and daughter Katie, 10 (pictured), who attended the concert of Ariana Grande at the Manchester Arena, are seen in Manchester, Britain, 23 May 2017. According to a statement released by the Greater Manchester Police on 23 May 2017, police responded to reports of an explosion at Manchester Arena on 22 May 2017 evening. At least 19 people have been confirmed dead and around 50 others were injured, authorities said. The happening is currently treated as a terrorist incident until police know otherwise. According to reports quoting witnesses, a mass evacuation was prompted after explosions were heard at the end of US singer Ariana Grande's concert in the arena. EPA/NIGEL RODDIS EPA Manchester explosion in pictures Mayor of Greater Manchester Andy Burnham and Manchester City Council Leader Sir Richard Leese speak to the media outside Manchester Town Hall after a suicide bomber killed 22 people, including children, as an explosion tore through fans leaving a pop concert in Manchester Dave Higgens/PA Wire Manchester explosion in pictures The media gather behind a police cordon in Manchester Getty Images Manchester explosion in pictures Flowers left close to the Manchester Arena, the morning after a suicide bomber killed 22 people, including children, as an explosion tore through fans leaving a pop concert in Manchester Danny Lawson/PA Wire Manchester explosion in pictures Ariana Grande concert attendees Karen Moore and her daughter Molly Steed, aged 14, from Derby, leave the Park Inn where they were given refuge after last night's explosion at Manchester Arena Getty Manchester explosion in pictures Signs saying 'We love Manchester' are displayed in a window in Manchester, England Getty Images

But, strikingly, Mr Corbyn delivered his speech just days after the tragedy and while the police and intelligence services continue to conduct an investigation it is expected to take many months.

His pledge to change foreign policy suggests he would end involvement in air strikes against Isis in Iraq and Syria, where 1,250 British military personnel are stationed.

The contrast with Ms May could not be starker, after she backed Nato becoming a formal member of the coalition fighting in the region.

Mr Corbyn’s speech comes after Ukip claimed the Prime Minister shared the blame for the Manchester attack because she failed to prevent Abedi from returning to Britain.

“It is also a dereliction of duty to allow jihadis to return to this country, including it seems, Monday night’s terrorist,” said Ukip leader Paul Nuttall.

Suzanne Evans, Ukip’s deputy chair, added that Ms May “must bear some responsibility” for the deadly attack, because she forced through police cuts and failed to cut immigration.

Speaking in central London, Mr Corbyn called for “the solidarity, humanity and compassion that we have seen on the streets of Manchester this week to be the values that guide our government”.

Britain must ensure “we never surrender the freedoms we have won and that terrorists are so determined to take away”, he added.

The election campaign will get back up to full speed on Friday, after the cross-party agreement to put activities on hold as a mark of respect.

Even without Mr Corbyn’s speech, attention was likely to focus on the stance of the party leaders on security issues, police funding and the terrorist threat.