Britain is to further tighten benefits for European workers, the latest in a series of measures aimed at cracking down on immigration, dpa quoted the Department for Work and Pensions as announcing on Wednesday From March, immigrants from the European Economic Area will have to prove that they earn around 150 pounds (250 dollars) a week in order to qualify for "worker" status, which gives them access to better benefits. "As part of the government's long-term economic plan we have taken action to make sure our economy delivers for people who want to work hard, play by the rules and contribute to this country," said Work and Pensions Secretary Iain Duncan Smith.