Lord Frost has issued a stark warning over Sir Keir Starmer's plans if he comes to power, suggesting he would take Britain back to the European Union.
Speaking to GB News at the Alliance for Responsible Citizenship (Arc) Conference in London, he said it would be "unwise" to elect Labour, warning the party "clearly wants to get us back closer economically and politically".
WATCH: Frost issues stark warning over Starmer's plans for Brexit
While the former Brexit negotiator admitted that Starmer could not take Britain back into the EU "in one go", he added: "I think he wants to do it, and I think, if we are unwise enough to elect Labour we will see this inching back."
Asked if he worries about Labour bringing us closer to the EU, Frost told GB News: "I do a bit, I must admit.
"I don't think he could take us back into the EU in one go, given everything that's happened, but I do think that he wants and the Labour Party clearly wants to get us back closer economically and politically.
"And, you know, maybe that means accepting EU laws in some areas, softened trade, accepting EU migration rules - even though one of the main motivations obviously of the Brexit referendum was to reduce migration.
"But I think he wants to do it, and I think, if we are unwise enough to elect Labour we will see this inching back."
However, Starmer himself has repeatedly ruled out a return to the European Union - despite backing a referendum previously.
Speaking to GB News, Frost also pushed back against concerns that Brexit has been a failure, saying: "A lot of people have talked themselves into this belief that Brexit is somehow failing.
"But if you look at the reality, our trade is the highest it's ever been, growth is faster than most of the other European countries, we've changed the entire economic model of the country and it doesn't even show up in the growth figures.
"So why do people have this feeling it's not working? It really is working, we need to have confidence in it."
Frost also dismantled Starmer's plans for both a migration pact and a renegotiated Brexit deal, outlining some of the major tradeoffs the party would have to make in order to get any deals over the line.
He warned that the UK would have to "pay a price" if it wanted to secure a return deal with the bloc.
He said this could involve either the acceptance of EU laws or a financial cost.
The Labour leader unveiled his new plan to tackle illegal migration earlier this year, which will involve a cross-border approach to tackling the gangs.
He said he is planning to seek an EU-wide returns agreement for asylum seekers who arrive in Britain. This could involve the UK agreeing to a quota of migrants it will be forced to accept from the EU each year.
Asked if the UK would have to hand money or power to Brussels in order to get the deal over the line, the former Brexit negotiator said: "For sure, every negotiation involves a set of tradeoffs and I think Labour is possibly still in the world where they think because they sound sort of nice and progressive and pro-European, the EU are going to give them any of these things without some sort of counter payment.
Starmer has also promised to secure a "better" version of the UK's post-Brexit trade agreement with the EU when it comes up for renegotiation in 2025
PA
"The EU just doesn't work like that, that is not how it relates to the rest of the world.
"And if you want some of these things then you're going to have to pay a price, whether its money, whether its accepting EU law or whether it's accepting something else we don't want - that is the reality of this.
"So I keep asking Labour what are you prepared to give up to get these things? And they don't have an answer."
Starmer has also promised to secure a "better" version of the UK's post-Brexit trade agreement with the EU when it comes up for renegotiation in 2025.
But Frost warned that such a move could mean accepting EU laws in some areas.
Labour has been contacted for comment.
