Former prime minister Tony Abbott has used a speech in London to call on European leaders to close their borders to asylum seekers or risk imperilling their nations.

Key points: Tony Abbott tells EU leaders to close turn back asylum seekers

Tony Abbott tells EU leaders to close turn back asylum seekers Says military action in Middle East must be maintained to counter Islamic State caliphate

Says military action in Middle East must be maintained to counter Islamic State caliphate Comments labelled "disappointing" by Australian refugee advocate

Comments labelled "disappointing" by Australian refugee advocate Watch Abbott's speech in full or read the transcript

Mr Abbott delivered the second annual Margaret Thatcher Lecture at a banquet in London to an audience of Tory ministers and Conservative Party members.

He used the occasion to promote the Coalition's hardline asylum seeker policies as a solution to Europe's migrant crisis, which has seen hundreds of thousands of people, mainly from the Middle East, cross into the continent.

He urged regional leaders to act by "turning around boats [and] denying entry at the border for people with no right to come".

"It will require some force, it will require massive logistics and expense; it will gnaw at our consciences," Mr Abbott said.

"Yet it is the only way to prevent a tide of humanity surging through Europe and quite possibly changing it forever."

He outlined his concern that "misguided altruism" was "...leading much of Europe into catastrophic error".

"No country or continent can open its borders to all comers without fundamentally weakening itself," he said.

He cautioned, "too much mercy for some necessarily undermines justice for all".

Mr Abbott called for more to be done to counter the ideology behind extremist groups, such as Islamic State.

"It's a pity that the recent UN Leaders' week summit was solely about countering violent extremism ... and not abound not about dealing much more effectively with the caliphate that's now the most potent inspiration for it," he said.

Mr Abbott acknowledged the lack of public appetite for escalating involvement in the Middle East, but he emphasised the need for military action.

"Leaving anywhere, even Syria, to the collective determination of Iran, Russia and Daesh [Islamic State] should be too horrible to contemplate," he said.

Abbott's views in hot demand: Turnbull

Prime Minister Malcolm Turnbull refused to be drawn into the debate about Mr Abbott's comments.

"Tony has given a speech. I will leave others to run the commentary on it," he said.

"He has obviously had a remarkable career in public life, including two years as prime minister. We owe him a great debt for that.

"His views are in hot demand everywhere in the world."

However, Opposition Leader Bill Shorten said Europe's asylum seeker crisis was complex.

"I am not sure Tony Abbott on a victory lap giving a Margaret Thatcher Lecture is exactly what Europe needs to solve its problems," he said.

"I think the issues there are issues which the Europeans have to grapple with and simply saying Australia has all the answers is not the right way to go."

Mr Abbott arrived at Guildhall in London with wife Margie by his side, after the pair spent time hiking in Scotland, including a visit to Hadrian's Wall.

The lecture, to honour former UK Conservative prime minister Margaret Thatcher, was attended by several Tory ministers in David Cameron's government and Conservative Party officials.

Some of Mr Abbott's current and former staff members attended the function, but not his former chief of staff Peta Credlin.

Abbott's comments 'disappointing, simplistic'

Refugee Council of Australia president Phil Glendenning slammed Mr Abbott's comments as "disappointing" and "simplistic".

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"In terms of what Mr Abbott's proposing in Europe, it would be an utter catastrophe if people fleeing from persecution were told to go back there, were pushed back to sea where they would likely drown," Mr Glendenning told ABC News Breakfast.

"I find it very disappointing that an Australian PM would say this."

Mr Glendenning took aim at Mr Abbott's claim he had stopped asylum seeker boats coming to Australia.

"It hasn't actually stopped people taking to the sea in our region," he said.

"The UN's recently reported there are some 53,000 people trying to seek safety and security in our region.

"So the boats have sort of been deflected.

"They've passed the problem on to someone else."

However, Mr Abbott received support from UK Independence Party leader Nigel Farage, who backed his stance as "heroic" and "absolutely right".

"There is a very big difference between being a civilised country that recognises that there are genuine refugees from time to time and having a lunatic policy, that I'm afraid [German chancellor Angela Merkel] has pushed, saying 'Please, world, come here, we're pleased to have you'," he told Radio National.

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