A planned customs union between Russia, Belarus and Kazakhstan could dent their plans to join the World Trade Organisation, the EU's foreign policy chief said on Wednesday.
Russia, which has spent 16 years negotiating to join the WTO, last year announced plans to form a customs union between Russia and its former Soviet neighbours Belarus and Kazakhstan.
That three-way union is expected formally to come into force from July 1, despite a dispute in recent weeks between Russia and Belarus over oil-export duties.
Speaking to the European Parliament in Strasbourg, the EU's high representative for foreign affairs, Catherine Ashton, said the pending union had raised concerns in Europe.
"We have no issues with customs unions in general ... but we are concerned when those hinder trade rather than promoting it," she said. "That appears to be the case with the proposed customs union."
Moscow suspended talks with the WTO last year after it announced its plans for the Belarus-Kazakhstan customs union, but is expected to resume the WTO discussions this month.
The EU said last month that Russia could join the WTO within a year, amid generally better ties with Brussels and Washington.