The new benefit Universal Credit is harming vulnerable Scots according to a new report from Citizens' Advice Scotland.

The charity said the introduction of the new system had revealed major problems which must be fixed before it is rolled out to more people on benefits.

Particular problems exist with delays in payments, unfair sanctions for those deemed to have broken the rules, and technology foul-ups, CAS said, while the transfer of some welfare powers to Holyrood could also cause problems.

Universal Credit brings together job-seekers allowance, housing benefit and half a dozen other benefits into one simplified system.

However CAS has spent a year analysing the impact of the new system on Scottish Citizen's Advice Bureaux clients, and said changes need to be made.

Spokesman Rob Gowans said "Anything that seeks to simplify the system and make it easier and more efficient has to be welcomed. So we have always supported the policy and we want it to work. We also understand that any new system is bound to have teething problems, and the government was right to roll out it slowly so that these could be identified.

"We are presenting the problems we have seen, so that they can be fixed. However, in the past Ministers have been slow to act in fixing such flaws, and often deny their existence, despite overwhelming evidence. If the problems we have identified are not addressed, then the system really could cause serious detriment to some of the most vulnerable people in our society."

The CAS report lists the flaws in three categories: problems in the design of the system, problems in its administration and possible future challenges. Other concerns include a six-week wait to receive a first payment, having claims primarily submitted online when around 20% of users struggle to use the internet and 'numerous' changes made to UC by George Osborne's 2015 budget and autumn statement.

The report comes as a separate report commissioned from the Department for Work and Pensions showed that cutting benefits does not encourage people to try harder to find work. The study, carried out in Oxford by the city council and the DWP suggested that every pound docked from a long term jobless claimant’s income through housing benefit cuts, reduced their chances of finding work by two per cent.

A Department for Work and Pensions spokesman said:“The reality is that Universal Credit, which is now available to all single jobseekers across Scotland, is revolutionising welfare, with claimants moving into work faster and earning more than under the old system.

“We are working closely with Holyrood on the transfer of a raft of new powers on tax and welfare that delivers for the people of Scotland.”