Media playback is unsupported on your device Media caption Owen Smith suggests IS talks

Labour leadership challenger Owen Smith has suggested the so-called Islamic State could be involved in negotiations with the West in the future.

Mr Smith said all conflicts ended in "dialogue", during a two-hour debate with Jeremy Corbyn on the BBC's Victoria Derbyshire programme.

The Labour leader said he would not negotiate with so-called Islamic State.

The pair also clashed over allegations of abuse within the Labour Party, nuclear weapons and the EU referendum.

Commenting after the debate, Mr Corbyn's campaign team called Mr Smith's comments on IS "hasty and ill-considered".

But Mr Smith stressed he was not suggesting "we're going to be able to bring ISIS round the table right now."

Pressed on how soon it might happen, he told BBC News: "We don't know. We would all hope that it happens quickly, we would all hope they stop being a murderous terrorist organisation and try and bring about peace. But at the moment there's no evidence of that, is there?"

The audience of 100 Labour supporters in Nottingham repeatedly expressed concern about "abuse" between the two sides in the leadership contest.

Mr Smith said Labour had become divided, with Mr Corbyn's supporters feeling he was the "only socialist in the Labour Party".

"The truth is I'm not a red Tory, I'm not a Blairite, I'm a socialist same as you," Mr Smith said.

But when Victoria Derbyshire suggested to the Labour leader the atmosphere within the party had become "toxic", Mr Corbyn hit back, asking: "Well, how do you know?"

Mr Corbyn said he had attended Labour events all over the country with "people of all shades of opinion having an intelligent, respectful discussion and debate".

"That is how we should do things at all times," he said.

Analysis

By BBC Political Correspondent Adam Fleming

We knew that there were few major policy differences between the two men and that the real division was over who had the qualities to lead the Labour Party.

Jeremy Corbyn failing to recognise Ant and Dec is the sort of thing that might get talked about in the pub on Wednesday night, while the political establishment is wondering whether Owen Smith really does think there will come a time for talks with so-called Islamic State.

The main thing I will take away from the debate is just how upset, angry, confused and hurt ordinary Labour members are about the state of their party.

The two men also clashed over who was responsible for Labour's low opinion poll ratings, with Mr Smith repeating his assertion that Mr Corbyn could not lead the party to power and Mr Corbyn urging him to rejoin the shadow cabinet.

Media playback is unsupported on your device Media caption Jeremy Corbyn: "I have been robust on abuse" in Labour

Media playback is unsupported on your device Media caption Labour's Owen Smith: I'm persuading people across UK

Media playback is unsupported on your device Media caption Labour's Jeremy Corbyn unable to recognise Ant and Dec

In a quick-fire question round, Mr Smith said being described as a "Tory" was worse than being described as a "smarmy nonentity" (a quote from Spectator columnist Rod Liddle).

And Mr Corbyn could not identify TV presenters Ant and Dec when shown a picture of them.

Peace talks

On foreign affairs, Mr Smith suggested the so-called Islamic State would eventually have to be brought into peace talks if there was to be a settlement to Syria's civil war.

Referring to his experience as an adviser to Labour's former Northern Ireland Secretary Paul Murphy, he said: "Ultimately all solutions to these sorts of international crises do come about through dialogue.

"So eventually, if we are to try and solve this, all of the actors do need to be involved.

"But at the moment, Isil are clearly not interested in negotiating."

He added: "At some point, for us to resolve this, we will need to get people round the table."

Asked the same question, Mr Corbyn said: "They are not going to be round the table. No."

Speaking after the debate, Mr Corbyn's leadership campaign described Mr Smith's on comments on IS as "hasty and ill-considered".

'No negotiation'

The spokesman said: "Jeremy has always argued that there must be a negotiated political solution to the war in Syria and the wider Middle East, and that maintaining lines of communication during conflicts is essential.

"But Isis cannot be part of those negotiations. Instead, its sources of funding and supplies must be cut off."

The comments were also seized on by the Conservative Party, with Tory MP and member of the Defence Select Committee Johnny Mercer saying it showed Mr Smith's "unfitness for leadership".

"It shows that whoever wins this increasingly bizarre leadership election, I'm afraid Labour just cannot be trusted with keeping us safe," added Mr Mercer.

But Mr Smith's campaign said he was "clear" there should be no negotiation with the so-called Islamic State, or Daesh as it is also known, "until they renounce violence, cease all acts of terror and commit themselves to a peaceful settlement".

"Owen's experience of helping to bring about peace in Northern Ireland is that eventually all parties who truly believe in delivering peace have to be around the table.

"In the Middle East at the moment that clearly doesn't include - and may never include - Daesh."