UPDATE (09:18 BST): Owen Smith has appeared on BBC Radio 4's Today programme this morning claiming that the "lunatic" remark was a reference to himself.

Owen Smith has been urged to apologise for his "offensive and personal abuse" of Jeremy Corbyn after he labelled the Labour leader as a "lunatic" on Tuesday night (23 August). The former shadow work and pensions secretary reportedly made the mental health-related comment during a rally in Hammersmith, London.

"What you won't get from me is some, you know, lunatic at the top of the Labour Party, you'll have someone who tries to form a coherent narrative about what's wrong with Britain," Smith told his supporters.

A spokesperson for the Jeremy For Labour campaign urged the Pontypridd MP to apologise to people suffering with mental illness. "Owen Smith has degraded this contest by descending into personal abuse," the spokesperson said.

"He should apologise to people suffering with mental illness, many of whom would have been dismayed and upset to hear such offensive language used in public by a Labour politician.

"He should also withdraw his remark, and spend time with people suffering from mental health problems to develop some sensitivity in his use of language. This is simply not the language that someone standing to lead our party should use, and it injects an ugly tone into this contest that no Labour member wants to see."

The incident is the latest gaffe from Smith, a former radio journalist, after promising to "smash" Prime Minister Theresa May "back on her heels" and revealed that he would want self-styled terrorist group the Islamic State (Isis) "around the table" for peace talks over Syria.

The comment is also likely to draw attention away from another of his flagship policies announced on Wednesday (24 August). Smith has promised to block the government triggering Article 50 of the Lisbon Treaty, the mechanism to split from the EU, if May does promise a second referendum or general election to "ratify" any Brexit deal.

"The British people were lied to by the Leave campaign – they deserve to have a say on whatever exit deal the Tories strike with the EU. Theresa May says that 'Brexit means Brexit' – but nobody knows what Brexit looks like," he said.

"It could involve trashing workers' rights and environmental protections, opening our NHS up to foreign competition, making it harder for us to trade with our neighbours and damaging our economy.

"I'm a passionate pro-European, and I will fight tooth and nail to keep us in the EU."