DEPUTY Prime Minister Nick Clegg is promising action "shortly" to lift the cap that prevents the effective wiping out of the so-called bedroom tax in Scotland.

The Holyrood Government has been asking the Department of Work and Pensions (DWP) for the cap on Discretionary Housing Payments (DHP) to be lifted as the best mechanism for alleviating the impact of the benefit cut for those deemed to be under-occupying social sector homes.

The leader of the Liberal ­Democrats, in Aberdeen for the Scottish LibDem spring ­conference, was responding to comments from the party's ­Scottish leader Willie Rennie that the bedroom tax was not working and should be scrapped.

Mr Rennie, who defended the spare room subsidy at conference last year, said: "The principle behind it I can understand but, to be honest, I don't think it is working as it was intended and I think it should just go, and it should go quickly."

This was put to Mr Clegg during a briefing ahead of his conference speech.

He said: "I actually strongly agree that of course a policy like this needs to be kept under constant review and should of course be amended and changed as things go along.

"There are some changes we can deliver in this coalition Government and there are some that the Liberal Democrats can't because of the Conservatives."

The Scottish Government says DWP rules mean it is constrained in what it can legally spend on DHPs, and it has written to the UK Government requesting this cap is removed.

Mr Clegg said: "There are some councils in Scotland who have run up to the limit of the funds they have available to them for discretionary housing payments. There is this limit - a cap in effect - on what councils can use which I think needs to be addressed, and we will be making an announcement about that shortly.

"This is obviously a highly controversial policy, and one we are constantly keeping under review. I have insisted that there are more funds available to deal with the hard cases."

SNP MSP Linda Fabiani, who sits on the Scottish Parliament's Welfare Reform Committee, said the LibDems were equally to blame with the Tories for the bedroom tax and said Scottish Government Ministers had repeatedly raised the issue of discretionary housing payments with counterparts at Westminster.

She added: "Only a Yes vote and independence will give the ­Scottish Parliament the power to scrap the Bedroom Tax.

"In the meantime, the LibDems and Tories should get out of the way and let the Scottish Government get on with the job of mitigating the Bedroom Tax for all those affected."

A survey based on Freedom of Information requests from the BBC suggested that only 6% of social housing tenants facing the penalty had been able to move to a smaller property, but the UK Government said it was 8% after one year, which was "on track" with their original intentions.

Shadow work and pensions minister Chris Bryant said: "Trapped with nowhere else to go, thousands of people have had no choice but to fork out an extra £14 a week.

"David Cameron's Government have pretended this was all about helping people who are overcrowded, but in truth the bedroom tax is a cruel, unfair and appallingly administered policy."

Claudia Wood, chief executive of the think tank Demos, said: "The Government said the bedroom tax would encourage people to downsize and reduce housing benefit costs.

"In reality, a chronic shortage of smaller properties means many cannot move.

"Today's figures show more than one in four households affected have fallen into arrears for the first time, and if the problems worsen then evictions come at a price. Evicting someone can cost over £5000."

A Downing St source said: "The Chancellor is clear that the UK Government will not stand in the way of the Scottish Government if it wants to increase the amount it spends on discretionary housing payments.

"He expects to make an announcement soon."