Most people support a change in the law to ban unpaid internships that last more than four weeks, new research suggests.

A poll by the Social Mobility Commission found that four out of five people believe firms should advertise work experience and internship placements rather than organise them through informal networks.

The survey of almost 5000 adults also revealed three out of four supported a change in the law.

Former Labour cabinet member Alan Milburn, who chairs the independent body on social mobility, said: "Unpaid internships are a modern scandal which must end. Internships are the new rung on the career ladder.

"They have become a route to a good professional job, but access to them tends to depend on who not what you know and young people from low income backgrounds are excluded because they are unpaid."

The poll was published ahead of the second reading of Lord Holmes of Richmond's Private Member's Bill in the House of Lords proposing a ban on unpaid work experience or internships lasting four weeks or more.

Lord Holmes said: "The practice is clearly discriminatory, crushes creativity and competitiveness and holds individuals and our country back. It's time we consigned them to the past, to the novels of Dickens."