Rishi Sunak's flagship policy to stop Albanian migrants crossing the English Channel in small boats is unlikely to reduce overall illegal immigration because of "infinite" demand, Home Office sources have warned.
The prime minister's five-point-plan, launched last month, specifically targets people arriving from Albania after the Eastern European country accounted for more than a third of channel arrivals in 2022.
However, a senior source within the Home Office has told Sky News this will not significantly reduce migrant crossings.
"Even if you stopped any more Albanians coming across, the boats would still travel", they said.
"Their places on the boats would be filled by Somalis, Eritreans or Afghans who can't afford to pay as much as the Albanians are paying.
"There is an almost infinite number of people who want to come to the UK."
Last month, four migrants died after the small dinghy they were travelling in at night capsized.
Forty-three others were rescued in an operation involving the RNLI, the UK and French coastguard and the Royal Navy.
A lack of Albanians onboard may have meant the boat was not initially intercepted, as British security services are understood to monitor Albanian mobile phones in Northern France.
Around 33,000 of those arriving in Kent in the first nine months of 2022 were from Albania. This amounted to more than 30% of arrivals, compared to just 3% in 2021.
Officials have identified a common route which starts with a low-cost flight from the Albanian capital Tirana to Brussels, followed by a two-hour journey by road to Calais, and finally a small boat across to the Kent coast.
Mr Sunak announced a raft of measures in December to tackle illegal immigration, including a "new agreement and approach" with Albania's prime minister.
This includes Border Force officers being embedded at Tirana airport for the first time, new guidance that Albania is a "safe country" being issued for caseworkers, and the recruitment of 400 new specialists to expedite Albanian asylum applications.
The PM claimed his plan would mean the majority of claims are rejected and thousands returned on weekly flights until all the Albanians in the immigration system backlog have been removed.
Responding to the claims made to Sky News, a Home Office insider said: "No one is saying illegal migrants from Albania is the only issue we face.
"That's why the prime minister and the home secretary have a plan to tackle illegal migration across the Channel in small boats, irrespective of the nationality of those making the journey, and they will be bringing forward new legislation to target this as soon as possible."