MPs have warned that the system which checks the competency of overseas doctors working in the NHS needs to see "immediate changes".
The Health Select Committee claims patients' lives could have been saved if the General Medical Council (GMC) had greater powers to vet doctors, including assessment of their language ability.
The damning report followed the death of a Cambridgeshire patient who was killed by a German doctor after receiving a lethal dose of diamorphine.
David Gray died in 2008 when doctor Daniel Ubani administered 10 times the normal dose of the drug.
Even though it regulates doctors, the GMC is prevented by law from checking the language skills of medics or fully assessing their competency.
The committee heard there was difference of opinion between the GMC and the Government on whether the law could be amended without facing sanctions from Europe.
The report said: "If the GMC had been able to check the language skills and clinical competence of EEA doctors wishing to practise as GPs, lives might have been saved."
The report also said that, as a matter of "extreme urgency", the Government should make changes to the European Directive before it is due to be revised in 2012.
This would enable the GMC to "test the clinical competence of doctors and undertake systematic testing of language skills so that everything possible is done to lessen, as soon as possible, the risks of employing another unsuitably trained or inexperienced doctor in out-of-hours services".