[Bucharest] British Prime Minister David Cameron said on Wednesday that Britain wants to stay in the European Union but only if the bloc carries out "difficult" reforms including limits to migrant benefits.
"I want Britain to stay in a reformed European Union. That is why I am seeking important reforms to address the concerns of the British people about the status quo," he told a press briefing during a visit to Bucharest.
"As (EU president Donald Tusk) said earlier this week, we are making good progress, but I recognise that some areas are more difficult than others, particularly the reforms I've proposed on welfare," he said.
The British leader last month formally laid out a list of demands to his EU counterparts which include a controversial bid to prevent EU migrants from claiming certain state benefits during their first four years in the country.
Mr Tusk said Monday he expects a deal at a summit in February to keep Britain in the bloc, despite a lack of consensus over the key demand on migrant benefits.
In a letter to European Union leaders, Mr Tusk warned that uncertainty over a potential "Brexit" was destabilising the 28-nation bloc.
Mr Cameron, who has promised to hold a referendum on Britain's EU membership by the end of 2017, had hoped to get a deal by a summit later this month but has now acknowledged that will not happen.
On Wednesday he said: "I support the principle of free movement, to work, it's a basic treaty right and a key part of the single market."
He added however: "It was never envisaged that free movement would trigger quite such vast numbers of people moving across our continent." A net migration rate in Britain of "well over 300,000 a year... is not sustainable," he said.