It will apply to both those migrants who have entered the country illegally and those who have overstayed their leave.
The immigration bill will make it illegal for businesses and recruitment agencies to only advertise job vacancies overseas. Companies will also be told when their employees’ visas expire.
It is claimed the measures will close a loophole that only allows migrants with leave to remain to be prosecuted if they work illegally. Currently those without leave sit beyond the scope of the law.
Cameron will say: “The truth is it has been too easy to work illegally and employ illegal workers here. So we’ll take a radical step – we’ll make illegal working a criminal offence in its own right.
“That means wages paid to illegal migrants will be seized as proceeds of crime, and businesses will be told when their workers’ visas expire. So if you’re involved in illegal working – employer or employee – you’re breaking the law.”
He will argue that “uncontrolled immigration” damages the UK labour market and suppresses wages.