The French-British pilot project "one in, one out" means that migrants who arrive in the UK in small boats can be sent back to France. In return, the UK will accept the same number of asylum seekers from France, provided they have not previously attempted to cross the channel and that they pass the British security checks.
50 migrants per week
UK Prime Minister Keir Starmer and French President Emmanuel Macron announced the agreement in July, and last week the EU Commission gave the "green light", according to the British Home Office.
British and international law prevents the UK from sending asylum seekers back to their country of origin before their application has been processed and rejected. However, they can be sent to safe countries that are willing to process their application.
It has previously been reported that only 50 migrants per week will be covered by the new agreement, which is far fewer than the over 800 who cross the channel every week.
Home Secretary Yvette Cooper tells the BBC that she does not want to put a figure on how many migrants will be deported under the agreement.
Of course, it will start with lower numbers and then increase, but we want to be able to expand it further, she tells BBC radio.
A precedent
The agreement is still seen as a breakthrough because it will set a precedent that migrants who cross the English Channel illegally can be sent back.
Opposition politicians from the conservative Tory have criticized the Labour government and say that the agreement will not make a difference.
The smuggling of people in small boats has put great pressure on Prime Minister Starmer, who has promised to stop the flow of migrants.
Around 20,000 migrants crossed the English Channel in small boats during the first half of the year, which is a new record for the period.
