Jeremy Corbyn is 'threat to national security'

Prime Minister David Cameron said Sunday that veteran socialist Jeremy Corbyn's election to the Labour leadership made the main opposition party a threat to Britain's national security.

"The Labour Party is now a threat to our national security, our economic security and your family's security," he said on his personal Twitter account, in his first response to Corbyn's victory on Saturday.

The Conservative leader's comments mirror those made by Defence Secretary Michael Fallon on Saturday, and by the centre-right party itself.

Corbyn, a co-founder of the Stop the War anti-war movement, advocates unilateral nuclear disarmament, ending austerity and increasing public spending.

The media battle comes ahead of a likely parliamentary vote on bombing Syria, one of the first foreign policy tests of Corbyn's leadership.

Corbyn was elected as Labour leader to succeed Ed Miliband on a landslide, gaining 59.5 per cent of the vote.

 Meanwhile, The deputy leader of Britain's opposition Labour Party yesterday said he would aim to convince new Labour boss Jeremy Corbyn of the merits of the Nato military alliance, addressing a split at the top of the party over defense and foreign policy.

 Corbyn opposes the renewal of Britain's Trident nuclear-armed submarine program and has advocated withdrawing from Nato.

Watson, who backs the renewal of Trident, also said he would definitely support Britain staying in the European Union at a referendum due by the end of 2017.

Corbyn was starting work yesterday on putting together a shadow cabinet, with several senior Labour figures ruling themselves out of serving under him.

However, Watson told BBC television there was "zero chance" of a successful coup against the new chief, saying moderates had to respect Corbyn's "huge mandate.