Britain's Foreign Office said the issue of granting citizenship "is a matter for member states." Romanian Foreign Minister Teodor Baconschi told the AP that "no foreign minister has opened this subject."
But clearly the prospects of a mass influx is a sensitive issue.
Sarah Mulley, of the Institute for Public Policy Research think tank, says that even though passport giveaways are likely to have a limited impact in Britain, they could influence the already heated public debate about immigration and will "raise questions about how the EU coordinates policies between countries."
About 1.4 million Slavs in Macedonia - where the average yearly income is just over $4,500 - are also eligible for EU passports from neighboring Bulgaria, which considers them Bulgarians with a dialect.
And then there are Bulgaria's Turks. Some 300,000 fled or were expelled in the 1980s, under a communist campaign of forced assimilation. Although most remain in Turkey, all have either opened a fast track to the EU by reclaiming their Bulgarian passports or have the right to do so - even as Ankara continues its struggle with Brussels over EU membership.
Budapest, meanwhile, plans to offer dual citizenship - and passports - to millions of ethnic Hungarians outside its borders, including 300,000 in Serbia and about 160,000 in Ukraine - countries with annual per capita incomes of just under $6,000 and $2,500 respectively.
But it's the Moldovans, who stand to benefit most.
With her Romanian passport in hand, Larisa Saptebani is leaving for Italy in 10 days to work as a care giver. She has been promised 1,700 euros - nearly $2,200 - a month, a dream wage more than 10 times what her countrywomen earn at home. (Associated Press)
