David Cameron has appealed for the public to "shop" illegal immigrants as he pledged to reclaim Britain's borders.
He also insisted the citizenship test for legal incomers would be rewritten to include questions on British history and signalled a fresh crackdown on forced and bogus marriages.
And in future, individuals applying to come to the UK for family reasons will have to show that they can speak English and have the financial means to support themselves as well as genuine family links in Britain.
Family migration made up almost a fifth of non-European Union (EU) immigration last year, with 50,000 visas issued, he told an audience at the Institute for Government in central London.
But a survey suggested that more than 70% of UK-based family sponsors had an income of less than £20,000 after tax, creating "an obvious risk" that they may become dependent on welfare.
Mr Cameron said the Migration Advisory Committee (MAC) would consider whether the minimum level of financial support should be higher and whether a "bond" from migrants could be demanded in some cases.
There will be closer checks on claimed relationships between spouses to weed out sham marriages for immigration reasons, including cases where couples divorce immediately after obtaining permission to stay and then make fresh applications relating to different partners.
He added that he wanted the coalition to "go further and be even tougher" on immigration.
"For our part in government, we are creating a new National Crime Agency with a dedicated border policing command which will have responsibility for safeguarding the security of our border," he said. "But I want everyone in the country to help, including by reporting suspected illegal immigrants to our Border Agency through the Crimestoppers phone line or through the Border Agency website.
"Together we will reclaim our borders and send illegal immigrants home."
