Bulgaria's Foreign Ministry announced the country could impose counter-measures after the United Kingdom and Ireland approved limitations on Romanian and Bulgarian migrant workers.
"We do understand how sensitive the migration issue is to the British people, but we believe it won't be solved by imposing limitations on the Bulgarian citizens," Dimitar Tsanchev, spokesman of the ministry, said.
He added the reciprocal measures may apply for citizens from any other country of the European Union that blocked Bulgarians and Romanians from their labor markets.
"Each member state has the right to impose such restrictions, as provided in our entry treaty, but we think that such a decision will put us on an unequal footing with the 10 member states that joined in 2004," ministry spokesman Dimitar Tsanchev said, adding London's decision was "disappointing."
He attempted to assuage British fears of a threat from migrants, citing official data.