The drummer of the band Blur who also practices as a solicitor has attacked the government's legal aid proposals, describing them as a disaster waiting to happen.

David Rowntree, who trained as a solicitor during the band's hiatus, criticised the government after it emerged that the heavy goods haulier Eddie Stobart will bid to run legal aid services if the government goes ahead with plans to outsource criminal legal aid. Stobart could be competing against other service companies such as Serco and G4S although they have yet to express an interest.

The Ministry of Justice will run tenders for legal aid in 42 regions. Firms will submit bids for three-year contracts, which can be extended by two years. The number of legal aid providers will be reduced from around 1,600 to 400.

Rowntree, who is also a Labour party activist widely tipped to stand as an MP, said he was "appalled and outraged" by the planned reforms and fears they will create a two-tier justice system: one for the rich and one for the poor. "Justice for one should be justice for all, regardless of means," he said. "As far as I can see these plans spell disaster."

He said the tendering process – where the cheapest bid wins – would be run by companies with no record of providing legal services, resulting in a dumbing down of the profession and a race to the bottom that could see people missing out on access to quality legal aid. "Cases will be run on the cheap by under-qualified, inexperienced, low-cost staff," said Rowntree. "And when you skimp on defence, you send the wrong people to prison."

People reliant on legal aid will be offered an "adequate service", he said. "The government proposals only require a lawyer to provide a just-above-acceptable service – 'adequate' is the word they use, which is staggering when you consider what's at stake. The results will be devastating for the general public who will lose the right to choose their own lawyer at a time when their liberty is on the line," said Rowntree, who is currently recording with Blur in Hong Kong.

Legal aid work often involves anti-social hours in police stations, and regular appearances at magistrates courts. "They do it because they believe in serving the community, and giving anyone and everyone a right to be innocent until proven guilty. It's not glamorous, but they are the cogs that oil our justice system and help it to run smoothly. They don't deserve the kicking the government is giving them," said Rowntree, who swapped his reliable income as a rock star to venture into the risky world of impecunious lawyers, "Legal aid criminal work is about as far from Ally McBeal as you can get. The rates have been cut back so hard that the work hardly makes business sense any more."

Trevor Howarth, group legal director for Stobart Barristers, who say they work with around 1,000 barristers, juniors and QCs, has said traditional legal aid firms are "wounded animals waiting to die", which appalled Rowntree.

"He may think that kind of vain macho posturing impresses people in the trucking industry, but in the context of criminal defence it's just pathetic. Are they really the words of a serious professional?" he said.

A Ministry of Justice spokesperson said: "Quality assured lawyers will still be available, just as they are now. Contracts will not be awarded to lawyers who do not pass set quality standards. We will continue to uphold everyone's right to a fair trial.With one of the most expensive legal aid systems in the world - £1 billion a year is spent just on criminal legal aid — we can no longer avoid examining how to deliver better value for every penny of taxpayers' money we spend."