* Countries say Britain classifying them as second-class
* British media have warned of "hordes" of migrants
* Romanian newspaper invites Britons to visit
By Sam Cage
BUCHAREST, Feb 1 (Reuters) - Romania and Bulgaria hit back on Friday at efforts to deter their nationals from emigrating to Britain, saying they were being stigmatised as second-class members of the European Union.
Transitional rules for the EU's two newest and poorest members will ease at the start of 2014, giving their citizens the right to live and work anywhere in the 27-nation bloc.
In Britain, one of Europe's most popular migration destinations, the right-leaning press has warned that "hordes" will pour in from Bulgaria and Romania. One lobby group says it thinks 50,000 Bulgarians or Romanians will enter every year for the first five years.
On Friday, Romanian and Bulgarian members of the European Parliament wrote to European Commission President Jose Manuel Barroso to say their citizens' rights under EU law were at risk.
"We believe that a wave of hostile statements since the beginning of the year aims to stigmatise these citizens as second-class Europeans who pose a threat to the social systems just because they want to exercise their basic rights to free movement and work," the MEPs wrote.
Under pressure from public opinion and the eurosceptic UKIP opposition party, Britain's Conservative-led coalition is looking for ways to curb immigration within EU rules.
Asked about the MEPs' letter, a spokeswoman for Prime Minister David Cameron suggested the British government was not targeting Romanians and Bulgarians in particular:
"The prime minister has made his views clear about the benefits immigration can offer in terms of (attracting) the brightest and the best, and what we don't want to do is see any abuse, but that's not necessarily directed at any particular country or individuals."
"NO TO WELFARE ABUSES"
She said Britain was working with other states to try to limit abuses linked to free movement across the Union, but declined to comment on reports that it was considering an advertising campaign to deter Romanians and Bulgarians.
"If people can offer a positive contribution to our economy then of course that's welcome, but what we don't want is people necessarily abusing our welfare and benefits system."
Immigration is one of the public's biggest concerns and UKIP - which pledges to end "mass, uncontrolled immigration" - is threatening to draw a substantial number of votes from Cameron's Conservatives in the 2015 election.
Many eastern Europeans, including Poles, Hungarians and Czechs, have come to work in Britain since their countries joined the EU. Government data published on Thursday showed that Polish was now Britain's second most commonly spoken language.
Romania and Bulgaria joined the EU in 2007, three years after their central European neighbours, and millions of their citizens have already left to work in countries such as Italy and Spain, which have been easing restrictions since 2009.
But the two Balkan countries still lag behind in establishing strong legal systems to tackle organised crime and corruption.
In addition to the restrictions on migration, they are still excluded from the passport-free Schengen zone and their justice systems are subject to special monitoring by Brussels.
British media have said the government is considering an ad campaign to remind Romanians and Bulgarians of restrictions on state benefit payments - and of Britain's damp, windy weather.
Romania's Gandul newspaper ran a series of spoof adverts on Friday saying Britons would be welcome to come and sample better food and cheaper beer, and noting that Prince Charles owns property in Transylvania.
"We may not like Britain, but you will love Romania," it said. "Why don't you come over?" (Additional reporting by Angel Krasimirov in Sofia and Andrew Osborn in London; Editing by Kevin Liffey)