A Liberal Democrat Cabinet minister has voiced concerns over reports that David Cameron is prepared to take on Brussels to impose tougher conditions on European migrants.
The comment come amid fears about the number of Bulgarians and Romanians expected to come to the UK from January.
The Prime Minister is reported to be considering extending the length of time that new arrivals have to stay in the country before they gain access to benefits.
The Sunday Times said one option under consideration was requiring incomers to prove they have been resident for a year - four times the current three month threshold - before they can claim handouts.
The move could trigger a clash with the European Commission, which prevents member states from discriminating between their own citizens and those from other European Union members.
Tory Education Secretary Michael Gove told BBC1's Andrew Marr Show: "The Prime Minister ... struck exactly the right note on migration, which is to celebrate the achievements of people who come here, which is to recognise that migration has to work for people who are already here from whatever background.
"But when it comes to new migrants from accession countries in the EU, we need to look properly at the benefits system here to make sure people are coming here to work and contribute, not to take advantage of what is rightly a generous welfare system."
But Lib Dem Scottish Secretary Alistair Carmichael said the plans were still under consideration in Government and said any approach should be discussed in Europe.
He told BBC Radio 5 Live's Pienaar's Politics he could "see the need for robust transitional arrangements" but he added: "I would need to be persuaded of that but I am prepared to look at the whole situation in the round."
He warned: "Potentially it might put us on the wrong side of the rest of the European Union. As a member state I don't want to find myself in that territory. It's something that we should be discussing with them, certainly."
Shadow home secretary Yvette Cooper acknowledged that the "pace of immigration was too fast, the level of immigration was too high" under Labour.
She told the Andrew Marr Show: "We already said last year there were changes the Government could make already within the existing rules and changes that they should argue for across Europe as well to make sure the system is fairer.
"I do think when people are coming to this country they should be contributing and so we have already said there are changes you could make to Jobseekers' Allowance so people can't come and claim Jobseekers' Allowance straight away.
"If the Government had done that nine months ago when we suggested it we could have had more progress made on this right now. It's important to recognise that most people who come to this country do come to work and to contribute."