More than 50 Conservative MPs have written to Rishi Sunkak calling for emergency legislation to curb the number of migrants crossing the Channel in small boats.
The letter says the prime minister should push through changes to modern slavery laws to allow "bogus asylum seekers" to be turned away more quickly.
Led by former Brexit secretary David Davis, the MPs claim a "simple change" could mean "economic migrants" travelling from "safe countries" such as Albania would be unable to seek asylum.
They argue that "people claiming they have been unwilling victims of human trafficking or modern slavery" should be returned "to their homes in the villages from which they came from".
"If they have really been taken against their will, then they could not reasonably object to being returned to their own homes," the letter said.
"The quirks in our modern slavery laws that prevent this are clearly in defiance of the aims of that law and should be removed."
The MPs argue the "straightforward and legally workable way of addressing the crisis" would be a "very strong deterrent" for those planning to risk the perilous crossing.
David Davis, the MP for Haltemprice and Howden in East Yorkshire, has previously written to immigration minister Robert Jenrick to raise concerns about moves to house asylum seekers in hotels in his constituency.
A government spokeswoman said: "We have made clear that there is no one single solution to stop the increase in dangerous crossings.
"We have also made clear that we will continue to use every tool at our disposal to deter illegal migration.
"We are expediting the removal of individuals by agreeing tailored bilateral returns agreements with partners like Albania, elevating it to a key priority for our foreign policy."
The letter comes after home secretary Suella Braverman was criticised over conditions in the Manston migrant processing centre, in Kent, where one man died of diphtheria.
She has also been under pressure for failing to slow the perilous crossings of the English Channel by people in small boats.
This week she admitted the government had "failed to control our borders" but blamed the influx of migrants at the hands of people smugglers for the overcrowding in Manston.
A Home Office source said Ms Braverman was "working flat out alongside the prime inister to bring in reforms to help stem the flow of migrants across the Channel".
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