David Cameron says EU immigration at 'reasonable level' 27 January 2014 Last updated at 10:57 David Cameron has said the numbers of Romanians and Bulgarians arriving in the UK since the last work curbs were lifted are at a "reasonable level." The prime minister made the comment as he urged Tory MPs not to endanger his plans to curb immigration, telling the BBC he shared their "frustration." The prime minister said the immigration bill contained "sensible" measures aimed at lowering annual net migration. Rebels want the bill to impose controls on Bulgarians and Romanians until 2018. Transitional arrangements limiting the work that Bulgarians and Romanians can do in the UK, in place since they joined the EU in 2007, expired on 1 January. The BBC's political editor Nick Robinson said talk that it could lead to an "invasion" of migrants "seemed absurd" so far given the small numbers who have come to the UK and the PM had now appeared to give his verdict. Paused But he said MPs were concerned about the number of arrivals over a long period and wanted the prime minister to add new restrictions to the government's immigration bill, which is returning to the Commons on Thursday. The prime minister, who is facing a potential rebellion, told BBC Radio 4's Today programme that his hands were tied over the issue as the UK had already extended the controls to the maximum seven years. "Those seven years are now up," he said. We are not allowed to extend them further under the current rules... we have done the extent of what we can do within the rules that were agreed by the last government. Mr Cameron suggested the bill had been "paused" to reflect on the initial response to the end of Bulgarian and Romanian controls and he now wanted to press ahead with the legislation. I think we can now see at the start of the year so far there looks to be a reasonable level of migration and I hope we can make progress with the bill because it does so many good things. The bill, he insisted, contained important measures to ensure migrants had to pay to use the NHS and to ensure those not entitled to be in the UK should not be get council housing or the right to endlessly appeal against deportation judgements. Real concerns While net migration - the difference between the number of people settling in the UK and those leaving - was a third lower than in 2010, Mr Cameron said he wanted to see it fall further. I completely understand and, in many ways, share the frustration of colleagues who would like us to go further. Nick Robinson said he expected the government to table amendments which would put in place much tougher controls on migration from countries that join the European Union in future. The prime minister has also hinted that future controls would stay in place until aspiring EU members reach an average income level much close to that of the UK and other existing EU members. Speaking on Sunday, Conservative MP Nigel Mills said he and his colleagues did not want to "crash" the bill but he wanted further "limited and proportionate" action. Absolutely the last thing I want to see is this bill go down but I think we do need to set out very clearly that we have real concerns about the level of EU immigration and that something needs to start being done. So, I don't want to crash this bill at all but I think there are some more measures needed in it.