© Chancellor John McDonnell
Newly appointed shadow chancellor John McDonnell once called the United Nations a "puppet of imperialist powers" at an anti-war rally in 2007, according to reports in the British media.

McDonnell also used his speech at the rally to pledge his support for a Ministry of Peace, which would replace the Ministry of Defence and focus on the UK's work on international security, the International Business Times UK reports.

He said he had spoken to the former US Democrat congressman on the "Departments of Peace" initiative.

"People thought this was George Orwell or something. What we wanted to do is no longer have ministries of war or ministries of defense, but to have ministries of peace so that our government and the US government signs up to becoming peace makers in the world, rather than warmongers as they are at the present," he said.

"We want to also take forward the debate on world governance - how we transform the UN from being a puppet of imperialist powers into a democratic organization that represents the world's people," he added.

Newly elected Labour Party leader Jeremy Corbyn has said he would not allow any British troops to be sent abroad to fight without the permission of the UN.

McDonnell has proved a controversial choice for shadow chancellor. Corbyn has faced criticism among Labour MPs and some trade unionists for appointing his closest ally to the top job. Critics of Corbyn's shadow cabinet said McDonnell is ill-suited to such a public position after it emerged that he had said all IRA fighters should be "honored" in 2003.

In an interview with Channel 4 News anchor Jon Snow, McDonnell defended his comments, saying he made the remarks when the peace process was "extremely fragile" and that he "might not have chosen the right words" to explain his commitment to the cause.

McDonnell also courted controversy when he once joked he would like to travel back in time to assassinate Margaret Thatcher.

Corbyn is a staunch critic of British foreign policy, and has vowed to scrap the Trident nuclear weapons program if he is elected into power. Speaking to Sky News, he warned against "mission creep" of the UK's involvement in Syria, adding he would not authorize British involvement without the backing of the UN.

The Conservatives have said Corbyn would present a "serious threat" to the UK's national security. "Whether it's weakening our defenses, raising taxes on jobs and earnings, racking up more debt and welfare, or driving up the cost of living by printing money - Jeremy Corbyn's Labour Party will hurt working people," Defence Secretary Michael Fallon said. "This is a very serious moment for our country - the Conservatives will continue to deliver stability, security and opportunity for working people."

His comments were echoed by Prime Minister David Cameron who tweeted that Corbyn's election had transformed Labour into a threat. "The Labour Party is now a threat to our national security, our economic security and your family's security," he wrote.