Migrants are being smuggled into the US by legitimate travel agents based in Europe, the State Department has said.

US authorities accused rogue agencies operating in Europe, Africa and the Middle East of orchestrating illegal immigration.

The State Department said it had sanctioned the owners and executives of agencies selling fraudulent travel documents as well as flights “designed primarily to facilitate irregular migration to the United States”.

Officials declined to say how many travel agencies were involved.

Reports at the end of last year claimed “pseudo-legitimate” travel agencies had organised trips to Mexico and then smuggled between 500 and 1,000 migrants across the border at any one time. CNN has reported that one nationality being targeted was Senegalese who were being lured to Europe and then to the US.

Immigration is a key battleground in the presidential election with Donald Trump positioning himself as the only candidate who can tackle the issue. If the Biden administration can convince voters that it is getting on top of illegal immigration that will hugely assist vice-president Kamala Harris in the tightest of races.

Ms Harris has been accused of presiding over the “worst invasion in US history” over repeated claims made by Trump that she was appointed Joe Biden’s “border czar” although the Administration denies that was ever her role.

In an announcement on Tuesday, the State Department said: “The United States is imposing visa restrictions today on multiple executives of travel agencies in Europe, Africa, and the Middle East.

“These companies prey on vulnerable people by operating services designed primarily to facilitate irregular migration to the United States through countries in Europe and the Western hemisphere.

“We will continue to engage with partner governments and the private sector to end this exploitative practice, which puts vulnerable people in harm’s way.”