Owen Smith has called Jeremy Corbyn “a lunatic” at a rally.

The Pontypridd MP and Labour leadership hopeful told supporters “what you won’t get from me is some, you know, lunatic at the top of the Labour party” while speaking in Hammersmith.

It represents a considerable racheting up of direct hostilities between the two candidates, who will discover which of the two has won on 24 September. At the start of the contest, Smith pledged to appoint Corbyn to the post of party president should he win.

Footage of the event was obtained by the Independent’s Tom Peck, who attended the rally.

"WHERE IS YOUR RECORDING!! [of Owen Smith calling Jeremy Corbyn a lunatic]" they demand. Well, it's here. pic.twitter.com/HWLa9JNNDk — Tom Peck (@tompeck) August 23, 2016

A spokesperson for Corbyn's campaign said: "Owen Smith has degraded this contest by descending into personal abuse. He should apologise to people suffering with mental illness, many of whom would have been dismayed and upset to 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."

Smith, speaking on Radio 4, apologised for "a poor choice of words", saying that the remarks referred not to Corbyn but himself. "Someone said I'd been running about like a lunatic earlier on", he added.

A senior source close to the leadership poured scorn on Smith: "Owen's biggest weakness is Owen. He has decent staffers, but it's lions led by a donkey".