MPs say they have "serious concerns" with Galileo, the multi-billion pound satellite navigation programme being proposed by the EU.
The Transport Select Committee set out what they call the lack of rigorous assessment of costs, benefits and risks, and their concern over how the project will be funded, in a report published this week.
Galileo was proposed by the European Commission in 1999, and 2.4bn euros are needed to take it to the next procurement phase after public-private partnership talks collapsed earlier this year.
The main benefits of the project are likely to be felt in road and rail traffic monitoring, road pricing systems, and air traffic control. Russia and the US both already run similar systems.
The cost of building and running the system is likely to be £10bn. The MPs say that, unless a rigorous cost-benefit analysis is produced, the government must do everything in its power to prevent the project - already delayed by 5 years - from going ahead.
Committee chair Gwyneth Dunwoody said, "The Government must stop this folly, and endeavour to bring the European Commission to its senses. The Commission is poised to spend billions of tax-payers' money on a satellite system without any realistic assessment of its costs and benefits. To fund this, it is prepared to break all the rules for prudent budgetary discipline.
"This cannot be allowed to proceed. We must have independent and up-to-date evidence that proceeding with Galileo is worthwhile."