An infringement procedure initiated by the European Commission against the UK for incomplete implementation of the free movement of persons directive is continuing.
The EC noted that Bulgarian and Romanian nationals working in the UK did not receive the same papers for permanent residence as other EU nationals.
The UK now has two months to harmonise its legislation in accordance with EU law or else face referral to the European Court of Justice.
The EC said London was entitled to keep the procedure for the temporary issue of work permits to Bulgarians and Romanians but those who had acquired worker visas were supposed to have the same documents as other EU nationals.
So far the EC has opened similar infringement procedures against the Czech Republic, Germany, Italy, Malta, Lithuania, Spain, Sweden and Poland,