Mehmet Ogutcu, who previously worked as an advisor to former Turkish Prime Minister Turgut Ozal, said Turkey’s decision to strike a customs union deal with the bloc had resulted in them taking orders from Brussels without having any say about trade deals.
And he stressed that if Britain went down the same road, it could expect similar treatment.
His remarks come against a backdrop of uncertainty over customs arrangements between Britain and the EU.
There have been suggestions that EU officials might agree to consult the UK – but not offer voting rights – if PM Theresa May agrees a u-turn over quitting the customs union, the arrangement which allows tariff-free trade throughout the block.
But Mr Ogutcu, who helped negotiate Ankara’s customs arrangement, said: “Being part of the customs union but not being able to make favourable trade deals with the rest of the world, and being subjected to unilateral EU rules and decisions in which you are not allowed to participate, do not look the most intelligent and win-win way of integration in terms of protecting your national interests.”
The UK needed to negotiate “a different generation” of the customs union, enabling it to strike trade deals with third-party countries while protecting its EU market share, or otherwise accept the statues quo.
Mr Ogutcu, who is now chairman of UK-based think tank-Global Resources Partnership, added: “With no influence in decisions on free trade agreements with the rest of the world and no membership prospects, the customs union has effectively reduced Turkey to a semi-colonial status, as some politicians argue.”
He was speaking to The Sun, a day after The Institute of Directors (IoD) touted the the idea of a Turkey-style agreement once the UK leaves the EU next year.
Allie Renison, Head of Trade Policy told Sky News: “Turkey has a customs union arrangement with the EU’s customs union.
“There are currently ways being explored to upgrade and modernise it to give Turkey a bit more input into the areas, for example, when the EU negotiates trade agreements, to make sure the tariffs are met on industrial goods, they get access to the other countries markets as well.
“It certainly does exist as a precedent for a partial and limited customs union.”
Parliament will debate the decision to quit the customs union today, and will get a non-binding vote on the issue after peers inserted an amendment calling for continued membership into the EU Withdrawal Bill.
Heavyweights including Foreign Secretary Boris Johnson and Trade Secretary Liam Fox are vehemently opposed to the UK staying in the customs union, and could quit the Cabinet if Theresa May backs down, jeopardising her political future.
Brexit secretary David Davis yesterday told the House of Commons failure any u-turn would amount to “failure”.
Downing Street continues to insist the UK will be leaving the customs union after Brexit, and has denied that a defeat in the Commons today would not represent a ‘no confidence’ vote.