Britain is ready to consider alternative measures to control EU migration amid widespread opposition to a proposed curb on benefits, Foreign Secretary Philip Hammond has said.
Mr Hammond urged other member states to come forward with counter proposals if they did not like the UK plan to ban new migrants from the EU from claiming in-work benefits for four years.
His intervention came amid mounting speculation that David Cameron may be preparing to offer concessions on his re-negotiation proposals when EU leaders meet in Brussels on Thursday.
Arriving in the Belgian capital for talks with EU foreign ministers, Mr Hammond acknowledged other member states had raised "concerns" about the benefit curb but said that so far it was the only proposal on the table for dealing with the UK's concerns about the level of migration.
"So far we haven't heard any counter-proposals, we haven't heard any alternative suggestions that would deliver the same effect in a different way," he said.
"We have made very clear that if people have ideas that will deliver on this very important agenda for the British people we are absolutely prepared to listen to them and we are prepared to enter into a dialogue about them."
Downing Street, meanwhile, played down proposals by London mayor Boris Johnson that the UK could seek a Danish-style opt-out from EU laws to allow it to control migration.
The Prime Minister's official spokeswoman said the Danish opt-out related to the "niche" issue of restrictions on second-home ownership, whereas the changes Britain was seeking had much wider significance.
"Clearly we are looking for something more significant and far-reaching in terms of benefits applying to workers from across the EU," she said.
She added: "The Prime Minister is clear on the need to address the concerns of the British people ... about the level of migration from within the EU.
"This is his proposal on the table and his position hasn't changed since he wrote to (European Council president) Donald Tusk last month setting out the areas where we need reform."
Writing in the Daily Telegraph, Mr Johnson warned other EU leaders had given Britain the "bum's rush" by refusing to accept Britain's "modest" proposals to restrict benefits for migrants.
He said that Mr Cameron was "much more Eurosceptic" than some other senior Tory figures and the UK must be offered reforms if the PM is to recommend continued membership in the in/out referendum promised by the end of 2017.
"The PM's suggestion was modest, and sensible. It has been recklessly disregarded," wrote Mr Johnson.
"These people are radically and dangerously misreading the Prime Minister if they think he wants to stay in the EU at any price. The David Cameron I know is much more Eurosceptic than some of his senior colleagues.
"We need to hear soon about ways in which the British Parliament can halt the tide of EU regulation, and ways in which we can regain some control of our borders."