The UK is looking at tighter controls to limit increased migration from Eastern Europe, Tony Blair has said.
UK could introduce moves to discourage migrants
The prime minister hinted at new measures to limit the number of people arriving from new EU countries.
Tory leader Michael Howard said nearly every other EU member state had imposed controls to limit the possible influx.
Mr Blair replied: "We will take whatever measures are necessary in order to make sure that the pull factor is closed off."
On 1 May 10 countries, including Hungary, Poland and the Czech Republic, are set to join the EU.
Mr Howard said that although he welcomed the new members, the UK had opted not to impose "transitional controls on the free movement of citizens".
Mr Blair replied: "The point you raise is a justified one. It is important that we recognise that there is a potential risk from these accession countries of people coming in.
"It's precisely for that reason now that we are looking at the concessions we gave and if it is right that closing off those concessions is going to mean we deal with this problem, then we will do so."
Mr Howard said that all the UK Government had done so far was to screen adverts on Slovak television asking people not to come to Britain.
That was despite the fact that the accession treaty enabling the new members to join allowed the UK the right to impose controls.
There have already been indications this week that the government is looking at issues like eligibility to benefits for people arriving in the UK - a system which Mr Blair suggested was "too generous" at present.