THE benefits system promotes "destructive behaviour" by removing the incentive for poor families to get a job, Chingford MP Iain Duncan Smith will warn.

In a speech today the Work and Pensions Secretary and architect of widespread welfare reforms is set to argue the current system is "destructive" as it encourages people to have more babies with the promise of further handouts, according to the Daily Telegraph.

Duncan Smith at a meeting today of the think tank Cambridge Public Policy will call for a return to the principles of William Beveridge, the founder of the welfare state, who warned that people cannot expect financial support from a "bottomless pit".

Meanwhile the Chingford MP has refused to appear before Members of the Scottish Parliament to answer questions on welfare reform.

Critics say the changes will unfairly impact on the poorest people.

The Conservatives hope reform, including the introduction of a universal credit for claimants, will save tens of billions of pounds a year.

The Liberal Democrats are threatening to block further cuts in benefits unless the Coalition also introduces new taxes on the rich.