In 2023, the previous Conservative government struck a deal to give France almost £500m over three years to go towards extra officers to help stop migrants crossing the Channel in small boats.
Shadow home secretary Chris Philp said the Labour government's plan "won't work because it will only see small numbers of illegal immigrants returned to France".
He added: "By definition, the vast majority crossing the Channel illegally will get to stay in the UK - so there is no deterrent."
Philp said the Conservatives had a deterrent in the Rwanda scheme, which aimed to discourage small boats crossings by sending some people who arrived in the UK illegally to the east African country.
But the plan was stalled by legal challenges and Labour scrapped the scheme before any migrants were sent to Rwanda.
Reform UK MP Lee Anderson said: "Instead of negotiating trade-style agreements concerning migrants, the focus should be on securing and closing our borders.
"Such a strategy would be more effective, less costly, and far simpler."
He added: "The priority must be reducing the number of illegal migrants in our country, not simply replacing them."
A Liberal Democrat spokesperson said a migrant returns scheme "would be a positive step that we'd support".
The spokesperson said: "We need to end these dangerous crossings. For far too long the Conservatives talked tough but failed to tackle the issue of small boats."
The Green Party has been approached for comment.
In 2023, Prime Minister Sir Keir Starmer said he would seek an EU-wide returns agreement.
But no such deal has come to fruition since Labour won the general election last year.
An EU-wide deal would be likely to face resistance from some European countries, such as Hungary, which has taken a hard line on migrants entering the country.
The UK government has so far focused on targeting people-smuggling gangs to bring down illegal migration, which is one of Labour's biggest challenges.
Earlier this year the government announced a series of measures to tackle people smuggling, including a new criminal offence of endangering the lives of others at sea with a jail term of up to five years.
Ministers have insisted there is no single "silver bullet" for solving the problem of illegal migration and the latest scheme is only one of a number of options being considered.