The Trump administration is to seek the criminal prosecution of every person caught trying to enter the US illegally, a policy that will likely split up more families and which the government hopes will act as a deterrent.

Under a new directive issued by Homeland Security Secretary Kirstjen Nielsen, agents are to pursue a “zero-tolerance policy” as outlined by Attorney General Jeff Sessions. It means that even if someone caught at the border illegally has a valid asylum claim, they could have a federal criminal conviction on their record, even if a judge later decides they have the right to stay in the country legally.

The separation of families, often for lengthy periods of times, was something that members of a migrants’ caravan that arrived at the US’s southern border late last month, were warned about by US lawyer providing free advice.

“We are the bearers of horrible news,” Los Angeles-based lawyer Nora Phillips told the Associated Press in Tijuana, while holding free legal workshops for migrants two weeks ago. “That’s what good attorneys are for.”

Confirming the new policy at an appearance in Arizona on Monday, Mr Sessions said: “If you cross the border unlawfully, even a first offence, we’re going to prosecute you.”

Donald Trump attacks Mexico for letting in 'caravans' of people

Speaking at a gathering of the Association of State Criminal Investigative Agencies, he added: “If you’re smuggling a child, we’re going to prosecute you, and that child will be separated from you, probably, as required by law. If you don’t want your child to be separated, then don’t bring them across the border illegally.”

Politico said the stepped up enforcement of federal immigration law comes as arrests on the border have climbed in recent months. It said Border Patrol agents caught about 38,000 people at the US-Mexico border in April, more than three times the level during the same month a year earlier.

Life on the US-Mexican border Show all 12 1 /12 Life on the US-Mexican border Life on the US-Mexican border Tijuana, Mexico A house stands next to a section of the border fence separating Mexico and the US Reuters Life on the US-Mexican border Tijuana, Mexico The border fence in Tijuana stretches all the way to beach Reuters Life on the US-Mexican border Tijuana, Mexico Migrants can often be spotted trying to cross the rusty barrier Reuters Life on the US-Mexican border Tijuana, Mexico Joaquin, 36, a chef from Guatemala who says he was deported from the US Reuters Life on the US-Mexican border Tijuana, Mexico A shack stands next to a section of the border fence Reuters Life on the US-Mexican border Tijuana, Mexico Tourists pose for a picture at the border Reuters Life on the US-Mexican border Tijuana, Mexico A family burns rubbish near the fence Reuters Life on the US-Mexican border Tijuana, Mexico Joaquin makes a living by selling rubbish Reuters Life on the US-Mexican border Tijuana, Mexico ‘Neither Trump nor the wall is going to stop anyone,’ says Pedro Reuters Life on the US-Mexican border Tijuana, Mexico Mexicans have built homes right next to the fence Reuters Life on the US-Mexican border Tijuana, Mexico Mexican Carlos, 27, who says that he was deported from the United States, heats up tortillas at his house near the double fence that separates Mexico and the US Reuters Life on the US-Mexican border Tijuana, Mexico A girl climbs stairs near a section of the fence

The DHS has said there had been a significant increase in apprehensions at the border over the 12 months, including the number of family units and “unaccompanied alien children”. “From April 2017 to April 2018, the number of apprehensions and inadmissible aliens tripled,” said a DHS official, asking not to be identified.

According to the AP, Mr Sessions said: “The Department of Justice will take up as many of those cases as humanly possible until we get to 100 per cent.”