A proposed deal between the United States and European Union is a “corporatist scam”, Ukip’s MP has said.

Douglas Carswell said that TTIP, which stands for the Transatlantic Trade and Investment Partnership, was not what its proponents made it out to be.

“Ukip [is] making clear we are the most staunchly free trade party in the UK,” he tweeted. “TTIP is not free trade. It’s a corporatist scam.”

Tellingly, the message was retweeted by Conservative MP Zac Goldsmith, a leading contender for his party’s nomination for Mayor of London.

TTIP’s proponents say it is a free trade deal that would benefit both the United States and European Union.

One controversial aspect of drafts of the deal would be to establish a quasi-judicial trade court to which the two blocs would be subject.

This could allow large corporations to ‘sue’ national governments for enacting any policy that potentially harmed their profits. Critics say that this would erode democracy and increase corporate power.

The deal is also controversial because of the secret way in which it is been negotiated, with press and campaigners relying heavily on leaks to determine its direction.

In pictures: The rise of Ukip Show all 8 1 /8 In pictures: The rise of Ukip In pictures: The rise of Ukip 1993: Alan Sked forms Ukip History professor Alan Sked had been active in anti-EU politics for a while beore he founded Ukip in 1993. He resigned from the party after the 1997 election, concerned that it was attracting far-right members, and has been critical of Ukip since. Picture: Reuters Reuters In pictures: The rise of Ukip 2005: Kilroy defects Former TV presenter Robert Kilroy-Silk founded Veritas in 2005, after a failed bid to become leader, and took many of Ukip's elected members with him. But the party slowly lost its popularity and didn't put forward any candidates in the last election. Picture: REUTERS/Kieran Doherty REUTERS KD/RUS In pictures: The rise of Ukip 2010: Farage becomes leader, again Farage had led Ukip from 2006 until 2009, when he stood down to fight against the Speaker, John Bercow, for his Buckingham seat. He failed to win the election and returned to lead the party in November 2010. Picture: REUTERS/Kieran Doherty REUTERS/Kieran Doherty In pictures: The rise of Ukip 2010: Ukip fights for election Nigel Farage was injured in a plane crash on polling day in the 2010 general election, but his party increased its success in the votes. It fielded 572 candidates and took 3.1% of the vote, though failed to win any seats. REUTERS/Darren Staples REUTERS/Darren Staples In pictures: The rise of Ukip 2013: Eastleigh gains Ukip's candidate Diane James got the highest ever number of votes for any candidate from the party, but was beaten by the Liberal Democrats. The surge in support gave Ukip confidence ahead of local and European elections later in the year. Picture: Reuters In pictures: The rise of Ukip 2013: Bloom kicked out Godfrey Bloom, who served as an Ukip MEP from 2004 to 2014, had the whip withdrawn in 2013 after sexist comments and an attack on a journalist. He sat as an independent MEP until 2014, when he ended his term in office. Picture: REUTERS/Luke MacGregor In pictures: The rise of Ukip 2014: European election success Ukip got a higher proportion of the vote than any other party in 2014's European elections, adding 11 new MEPs and taking its total to 24. REUTERS/Luke MacGregor In pictures: The rise of Ukip 2014: Carswell defects Douglas Carswell defected from Ukip at the end of August, and was followed by Mark Reckless at the end of September, who resigned from the Tories amid rumours of many more defections to come. Picture: REUTERS/Toby Melville

A Ukip spokesperson told the Independent that the party feared the destruction of public services by the deal.

"Ukip is a party that believes that free trade between people is the surest way to greater prosperity," he said.

"However the TTIP agreement is not a free trade deal, but one that favours big multinational corporates over the interests of smaller businesses, and most importantly the democratic right of people to set policy through elections.

"TTIP as it currently stands could hand the NHS lock, stock, and barrel to huge corporations against the wishes of the British people."

Labour said at the election that it supports TTIP in principle but that it would seek exemptions for the NHS and other public services to ensure they were not privatised under new rules.

The Conservatives and Liberal Democrats have expressed strong support for TTIP. Both parties dispute that the NHS would be affected.

The Green Party also opposes TTIP.

In recent weeks Ukip has stepped up campaigning against the deal. Earlier this month the party’s MEPs staged a protest in the European Parliament over the deal that saw the chamber descend into chaos.

At the European Parliament level the deal tends to be opposed by parties from the Left and Right, while centre-left and centre-right parties tend to be more positive about it.