Keir Starmer's plan to sanction people smugglers may fail because the UK will be relying on unwilling foreign governments to seize assets, a leading finance expert has warned.

Tom Keatinge, Director of the Centre for Finance and Security at RUSI, said Europe has little enthusiasm to sanction organised crime gangs, despite it being routinely deployed by the US in its war on the cocaine trade.

And this could lead to the UK going on a "noble charge and we look over our shoulders and there is absolutely nobody behind us", Mr Keatinge admitted.

The Prime Minister's plan hinges on countries like France, Germany, Turkey and Iraq deciding to "team up with you" and seize the smugglers' assets.

Tom Keatinge told the Daily Express: "When you are talking about a sanction against a form of organised crime, if you are going to freeze assets, you better have a way of seizing those assets and confiscating those assets.

"Where are the assets? The assets of these organised immigration crime kingpins are almost certainly not in the UK and almost certainly not in a jurisdiction the UK can access.

"So, what are you trying to do? You're hoping that the Germans, or the French or the Turks are going to team up with you.

"There's a risk that it is a noble charge, and we look over our shoulders and there is absolutely nobody behind us.

"There's an alignment of stars that are needed. There are plenty of people in Russia right now, oligarchs, subject to UK sanctions but you're never going to get the Kremlin to cooperate with you."

Asked if he has seen any sign other Governments are willing to work with the UK to make it a success, Mr Watlinge said: "No."

He then described how the National Crime Agency was keen to set up a sanctions regime to go after organised crime gangs.

But the sanctions expert revealed: "When we talked about it in Brussels, there was not the same appetite for introducing such a regime.

"In Europe they much more favour taking the law enforcement action rather than what some might view as the performance act of issuing sanctions.

"Are these countries willing to engage with the UK and deploy their resources to deal with a problem that they may view as something that the UK has chosen to make a political problem?

"It's no secret that the topic of organised immigration crime is not one in which the French and Brits see eye to eye on.

"If you want these sanctions to work, you are going to have to use them in co-operation with those other tools, and those other tools may well be in the hands of the French, the Germans and any other country you care to mention."

Mr Watlinge said sanctioning smugglers could then spook some of their associates from doing business with them.

He added: "It's very easy for policymakers to issue sanctions and talk tough.

"But people like me who have been following this stuff for 10-15 years find it quite hard to point to examples where the outcome that the politician, probably genuinely believed achieved."

Migrants and smugglers use an ancient payment system known as "Hawala".

This sees a third party pay a 'handler' in the migrants' home country. This money is then held until the migrant arrives safely at their destination.

The smuggler can collect his money from another handler in the country where he is operating. No physical money is ever exchanged under the 'Hawala' system.

The Daily Express understands detectives are finding it "difficult to investigate and track transactions" because there is no "actual movement of funds".

And the Prime Minister's sanctions regime will not have any impact on smugglers using this "infuriatingly effective" system.

Mr Keatinge said: "But if person X is subject to sanctions, and if hawala Y in Finsbury Park or somewhere else in the UK transfers money for person X, then at least law enforcement have a tool to use from a prosecution perspective.

"There's quite a few if, if, ifs, but it does create a point of leverage. Hawala is infuriatingly effective.

"At some point, the organised criminals - their size and their scope do touch the formal financial system so if you're a facilitator sitting in Turkey, you are earning money, you are going to go and buy a big house.

"The Mr Bigs do rely on the formal financial system to enjoy their proceeds of crime. This is all about asset denial."

Prime Minister Sir Keir Starmer has insisted sanctions can stop migrant smugglers from buying small boats.

Suspected traffickers will be sanctioned by name, allowing investigators to freeze their assets in Britain and those of any individual or business who supplies them with equipment or helps them financially.

The Prime Minister also claimed sanctions will become a deterrent to the migrant smuggling gangs.