Aircraft could be prevented from landing in the UK if it is believed they are returning suspected extremist jihadists from Syria or Iraq, under proposals set out by David Cameron.

The measures are among several outlined by the Prime Minister to the Australian Parliament in Canberra yesterday. It is part of a wider plan to ban suspected extremists, who travel abroad to fight, from the UK for two years.

British passports would be seized from suspected jihadists.

Mr Cameron faced a backlash from campaigners who warned the measures would leave some UK citizens stateless and could backfire.

He was accused by some ­opponents of "dumping suspect citizens like toxic waste".

The powers will be included in a counter-terrorism Bill to be tabled at Westminster this month.

Hundreds of men and women are thought to have gone abroad to fight in recent years.

They include former Aberdeen schoolboy Abdul Raqib Amin, 20, who appeared in a recruitment video for Islamic State (IS) earlier this year.

The Coalition Government has struggled to stem the tide of those leaving and to answer the question of what to do with them if they decide to return home.

Previous plans to bar suspected jihadis from coming back to the UK were dismissed by critics, including some Tory MPs, as potentially illegal.

But yesterday some of those opponents, including former attorney general Dominic Grieve, suggested the new, more restricted measures could comply with international law.

Under the plans individuals would be barred from returning from Syria and Iraq to the UK for at least two years. Exceptions would be those who face prosecution, or agree to bail-style reporting conditions or to undergo deradicalisation courses.

People proven to come back into the UK illegally could face up to five years in prison.

Airlines will also be ordered to comply with a "no-fly list" of those barred from travelling to the UK.

Any plane bringing banned individuals into the country could be prevented from landing.

Downing Street said it hopes the changes could be in place by January next year.

At a press conference in Australia, Mr Cameron said: "Successive governments have come to the view - and I agree with that view - that when you are facing an existential challenge and a challenge as great as the one we face with these Islamist extremists, we need additional powers as well as simply the criminal law."

He also said Facebook, Google and Twitter had a social responsibility to take propaganda by terror groups, including videos of beheadings, offline.

Shami Chakrabarti, director of the human rights gropup Liberty, said: "Dumping suspect citizens like toxic waste, abdicating your responsibilities to the international community, is a very strange way of promoting the rule of law. Summary powers to 'stop and seize' passports at airports will prove just as divisive and counter-productive as the infamous 'stop and search' powers that preceded them.

"When will our governments learn there are no short cuts to our security? It needs to be built on intelligence, evidence and justice, not speeches, soundbites and ever more new laws," she said.

Commons Speaker John Bercow also criticised Mr Cameron's decision to announce the proposals in a speech to the Australia parliament, rather than to MPs.