The new European Aviation Safety Agency is an "accident waiting to happen", MPs have said.
The new agency will set safety standards for airlines
A report by the Transport Select Committee has suggested EASA is a "half-baked, half-cock project" with poor management and resources.
The agency, set up in 2003, sets safety rules for new and current aircraft and will take over much safety regulation from national bodies.
The report was also critical of the UK's Civil Aviation Authority (CAA).
Both EASA and the CAA are studying the report and have yet to comment.
Committee chairwoman Gwyneth Dunwoody said EASA's "lamentable problems of governance, management and resources must not be allowed to compromise aviation safety in the UK in any way".
Enforcing the EASA's rules, including carrying out spot checks, will remain the job of Britain's Civil Aviation Authority (CAA).
The primary purpose of the report was to investigate the effectiveness of the CAA, which the report praised in part but said "many of those affected by its activities were dissatisfied with certain aspects of its work".
MPs said they were not convinced about the nature of communication between the CAA and the Department of Transport, and also believed the decision to stop the National Audit Office checking the efficiency of the CAA was wrong.
It also questioned whether the CAA paid enough attention to the light aircraft community and to environmental issues in general.
Mrs Dunwoody said: "There is much to be admired about the CAA. The exemplary safety record of aviation in the UK is a tribute to the dedication, experience and skill of the authority and its staff.
"There is a sense, however, that this success has been achieved despite, rather than because of, the institutional structure within which the authority must operate."
But her most scathing criticism was for EASA's effort at pan-European regulation.
"The UK must not transfer any further powers from the CAA to the agency until the government is assured that it is fit for purpose.
"The commission must examine closely the shambolic nature of the project to date, and apply the lessons learnt to future endeavours."