The Prime Minister warned them to be measured in how they talk about migrants to avoid playing into the BNP’s hands.
Mr Brown said: “The question is who has the best plan to control immigration, not who can appeal to our worst instincts of xenophobia.”
He stressed that Labour, the Tories and the Lib Dems have a duty to address genuine concerns about the impact of immigration.
And he vowed that Britons would benefit from new employment as the economy picks up. He also said that chefs and care workers, the biggest groups of non-EU workers, would be barred from entrance by 2014.
Mr Brown stressed illegal immigrants “are not welcome” and repeated his pledge to keep out unskilled non-EU workers.