Labour's bid to deport small boat migrants back to France risked turning to farce today as two deportation flights were blocked amid last-minute legal challenges.

An attempt to remove one migrant aboard an Air France flight from Heathrow to Paris' Charles de Gaulle airport was abandoned yesterday, followed by another today.

French charity Auberge des Migrants, which has mounted a campaign against the 'one-in, one-out' policy, said two deportations had now been cancelled.

It is thought lawyers for the migrants submitted late legal challenges shortly before the removals were due to take place.

Prime Minister Sir Keir Starmer’s official spokesman denied that the blocking of the first two flights meant the system was ‘a shambles’, or that ministers were powerless against the courts.

‘France is a safe country and we are expecting the first flight to take off imminently,’ he told reporters.

The deal agreed between the PM and president Emmanuel Macron in July is being hampered by last-minute 'modern slavery' claims and legal challenges under the European Convention on Human Rights, it is understood.

It will put Labour under further pressure amid Tory calls for the human rights treaty to be scrapped in all immigration cases.

Only last week Labour Attorney General Lord Hermer said leaving the treaty completely would be contrary to Britain's interests, and pointed out the PM had been 'absolutely crystal clear' the UK will remain a member.

Auberge des Migrants, along with British charity the Joint Council for the Welfare of Immigrants (JCWI), is urging members of the public to bombard Air France with complaints about the 'cruel' policy, and urging the company to pull out. 

The JCWI published a 'script' for members of the public to use when making complaints to Air France which said the removal of migrants was 'cruel'.

It went on to describe the deportations as 'violent, abusive and oppressive', and suggested airline pilots could refuse to fly if they believed a passenger may be 'disruptive'.

The JCWI's Griff Ferris accused Labour of operating 'racist human trafficking'.

He said: 'This latest cruel policy targeting people who come here to seek safety is just another grim attempt by a government flailing to appease the racist far-Right, for which it is increasingly becoming a puppet.

'Instead of playing games with people’s lives, the government should work with other European countries to create safe routes for people to move.

'We also call on Air France, and any other airlines which may be involved, not to be complicit in in this grim, racist human trafficking.'

Shadow Home Secretary Chris Philp, who predicted the deal would be hit with a slew of last-minute legal challenges, said the Government's scheme was a 'gimmick' and a 'joke'. 

The Tory frontbencher said: 'Labour has failed to deport a single illegal immigrant as they had promised - the first two flights took off without a single one on board.

'Only yesterday I told the new Home Secretary they need to completely repeal the Human Rights Act for immigration matters, but she refused and this is the predictable result.

'This Labour government is too weak to control our borders.

'The new Home Secretary is just as ineffective as the last one.

'The Government’s latest gimmick is a joke.'

Home Secretary Shabana Mahmood said yesterday the first migrant returns would take place 'as soon as possible'. 

She told MPs: 'International cooperation is the key for us securing our borders here at home, and assisting our international partners to do the same with their borders as well.

'I'm already in touch with my French counterparts. That was a landmark agreement, something the party opposite tried to achieve for many years, but they were all words, no action.

'It's this Government that struck that landmark deal, and we are working with our partners in France to get the first fight off the ground as soon as possible.'

The 'one-in, one-out' deal came into effect on August 7 and since then 5,435 small boat migrants have reached Britain.

About 100 migrants are thought to have been detained for potential removal under the scheme.

Since then, a number are thought to have brought legal challenges which blocked their removal.

As the Home Office attempts to carry out removals this week, further challenges are being brought at the last moment - meaning the migrants cannot be sent back until they are resolved. 

Plans to remove dozens of migrants aboard chartered aircraft are understood to have been abandoned in favour of placing small groups, or a single migrant, aboard scheduled services.

They would be accompanied by up to half a dozen Home Office escort officers.

The delay in the first removal will be a further blow for the Government as it comes under intense pressure to tackle the Channel crisis.

So far this year 31,026 migrants have arrived, up 38 per cent on the same period last year.

The British taxpayer will foot the bill for both sides of the deal, which will see migrants who came here illegally across the Channel exchanged 'one for one' with others still in France.

Migrants in France – such as those with relatives already in Britain or from countries which see high levels of applicants granted refugee status - will be flown here by the Home Office and handed a visa lasting up to three months while their final application is considered.

Officials insisted there will be 'rigorous' security checks even though the French will not hand over any personal details on migrants coming here – including any criminal records they may hold on them.

The Home Office refused to discuss details of the returns scheme.