The Justice Secretary had ordered officials to try out "flexible? hearings including evening sessions and full trials on Saturdays and Sundays after they were successfully used after the riots.

But while prosecutors have been promised overtime pay and extra time off for changing their working patterns, criminal defence solicitors were told they would not be paid more.

Leading firms say the changes would leave them out of pocket and damage their family lives, and complain the reforms have been forced on them without discussion.

They also say there are not enough cases to make it worthwhile and that the project will end up costing taxpayers more money as police, probation, prison and court staff will all need to be brought in out of normal office hours, as well as victims and witnesses.

Already some pilot schemes have been scrapped following a revolt while others have been scaled back. Elsewhere the Government is pressing on by drafting in lawyers from further afield, which could add to the costs of an exercise that was meant to improve efficiency.

The setbacks are likely to put further pressure on the veteran Conservative minister Mr Clarke, who is resisting attempts to be moved from his Cabinet post in the forthcoming reshuffle.

The Daily Telegraph has learned that:

• Youth courts in Nottingham were due to be convened every other Saturday and consider short cases involving defendants under 16, but this has been halted following objections from local lawyers.
• Magistrates courts across Staffordshire were going to be opened at weekends until court clerks said they would not turn up.
• Manchester Magistrates? Court is due to open for full trials on both Saturdays and Sundays from September, but almost all local solicitors are refusing to take part while more than 1,000 people have signed a petition opposing the initiative.
• A courtroom in rural Wales is being opened on Sundays despite fears by magistrates that it is not secure, while hearings will cease on the normal working day of Thursday as part of the deal.
• Magistrates courts in Newcastle are due to open at weekends this autumn but the Legal Services Commission is struggling to find lawyers to represent defendants after most local firms said they would boycott the plan.

So far the only projects that have got off the ground are those in South Wales, where courts are sitting from 9am until 6pm rather than 10am until 4pm, and in County Durham, where magistrates have been hearing full trials on alternate Saturdays.

Michael Robinson, a partner at Emmerson solicitors in the north-east, said: "There?s not enough work during the week, there are court rooms sitting empty.

"There are more important things in my life than standing in courts on a Sunday.?

Franklin Sinclair, a senior partner at Tuckers Solicitors in Manchester, said: "It is completely unnecessary, it?s simply so they can make an announcement at the Tory conference about the criminal justice system.

"If this is forced through it will ruin any relationship that we?ve got with them in the courts.?

Ash Bhatia, president of the Nottinghamshire Law Society, said: "It?s difficult to understand how this is of benefit to anyone.

"Had the Ministry of Justice properly consulted with the legal fraternity it may have been possible to identify areas and viable pilots in a proper way. It?s such a shame it has been forced upon all agencies.?

Lucy Scott-Moncrieff, President of the Law Society, which represents solicitors across England and Wales, has written to Mr Clarke to raise "significant concerns? about weekend court sittings.

She said lawyers backed some of his plans to speed up the criminal justice system, including using video links and "virtual courts? instead of bringing all prisoners and defendants to court.

But she went on: "If courts are to be operating as a matter of routine at weekends or out of normal office hours, this is likely to have a significant effect on our members? businesses.

"The Society will find it difficult to support these courts unless the costs and practical issues for the defence community are addressed.?

Small firms would find it difficult to provide staff on Saturdays and Sundays or to pay them extra, she said, and would have to renegotiate contracts. At the moment many solicitors already have to attend police stations on Friday nights and cover remand hearings on Saturday mornings.

The Ministry of Justice insisted that many courts already sit on Saturdays to deal with remand hearings and that the new pilots would only last for six months before being evaluated.

A spokesman said: "We are working with local areas to test whether a more flexible criminal justice system is able to better respond to the needs of the public, including victims and witnesses. This may include courts sitting outside of traditional hours during the week, sitting at weekends and increasing the use of video technology. This is to ensure we are able to respond to local demand and deliver swift and effective justice.

"We are currently working to finalise which areas will take part in the pilots and which models will be implemented, though we are expecting that extended Saturday and Sunday courts will only make up a very small proportion of the overall number of pilots. Decisions will be taken at a local level following discussions with partner organisations in the criminal justice system and the judiciary. The pilots will operate for a six month period and will be evaluated to inform any future decisions."