Ekrem İmamoğlu, the jailed mayor of İstanbul and a leading opposition figure in Turkey, has written an open letter to European Union leaders urging urgent modernization of the EU-Turkey customs union, warning that current trade arrangements are deepening structural imbalances and harming Turkish industry.
Writing from Marmara Prison in Silivri, where he has been held for more than 10 months, İmamoğlu said reform of the customs union has become unavoidable for both Turkey and the EU and should no longer be delayed.
Turkey has long sought to update the customs union agreement, which entered into force in 1995 and allows most industrial goods to circulate tariff-free between Turkey and the EU, its largest trading partner.
The agreement, however, excludes key areas such as services, public procurement and most agricultural trade, while binding Turkey to EU trade policy without giving it a role in negotiations with third countries.
İmamoğlu said recent developments have intensified those imbalances, pointing to the EU’s free trade agreements with the Mercosur bloc in South America and with India.
Because Turkey is bound by the customs union but excluded from such negotiations, he said, Turkish exporters face increasingly asymmetric conditions.
The EU has recently advanced major free trade agreements with third parties, including Mercosur — which includes Argentina, Brazil, Paraguay and Uruguay — and India. These agreements aim to reduce tariffs and expand market access once fully ratified.
Turkey does not automatically benefit from such deals, a situation critics say creates structural disadvantages for Turkish manufacturers and exporters.
İmamoğlu also criticized the European Commission’s “Made in Europe” initiative, warning that it could further marginalize Turkish products.
The proposal aims to restrict access for non-EU suppliers to parts of the bloc’s public procurement market by imposing local content requirements that could reach 70 percent for some goods, potentially affecting sectors closely integrated into European supply chains such as automotive manufacturing and green technologies.
“The Turkish industrial sector and business community are facing serious difficulties and uncertainty due to structural imbalances and discriminatory practices stemming from an outdated Customs Union,” İmamoğlu wrote, calling comprehensive reform an urgent necessity.
The European Commission proposed launching talks to modernize the customs union in 2016, but the process stalled amid political tensions and EU concerns over democratic backsliding and rule-of-law issues in Turkey.
İmamoğlu said progress on modernizing the customs union will inevitably be tied to democratic reforms, claiming that a future opposition-led government will rebuild the country on the basis of human rights and the rule of law and move faster than many expect.
Turkey has been an official candidate for EU membership since 1999, and accession negotiations began in 2005. However, the process has effectively been frozen in recent years amid growing tensions over democratic backsliding, rule-of-law concerns and Ankara’s foreign policy disputes with EU member states.
İmamoğlu also reaffirmed his support for Turkey’s eventual EU membership, describing it as a goal of historic importance for both sides.
He said the accession process will help address Turkey’s democratic shortcomings and make reforms durable while strengthening the EU’s capacity to deal with growing geopolitical and economic challenges.
“Democratic renewal in Turkey is not a distant ideal,” İmamoğlu wrote. “It is an urgent necessity.”
İmamoğlu was elected mayor of İstanbul in 2019 and re-elected in 2024.
He is widely seen as a potential challenger to President Recep Tayyip Erdoğan in the 2028 election. He was arrested in March in what critics describe as a politically motivated corruption investigation targeting the İstanbul Metropolitan Municipality and was later removed from office.
İmamoğlu’s appeal echoes a recent call from Turkey’s business community. Last Saturday leaders representing 26 Turkey–EU business councils urged EU institutions to reset relations with Ankara and move forward with modernizing the customs union.
In an open letter published as an advertisement in the Financial Times, they claimed that prolonged stagnation in EU–Turkey relations undermines strategic cooperation at a time of growing geopolitical and economic challenges and said an updated customs union will strengthen competitiveness on both sides.