Thousands of doctors from the ethnic minorities are being promised action to tackle "discriminatory" policies that leave them trapped in low-paid hospital jobs.

Amid claims of "racism" in the NHS, Tony Blair said yesterday that rules preventing many doctors trained outside Europe from becoming consultants were being reviewed. The Prime Minister insisted the problem was one of regulation "rather than racism" even though Alan Milburn, the Secretary of State for Health, acknowledged earlier that racism "probably" permeated some parts of the NHS.

The issue was raised by the Liberal Democrats, who complained that many doctors from outside the European Union were stuck in staff-grade posts while their white counterparts were promoted to better-paid consultancy posts.

Dr Evan Harris, the party's health spokesman, urged the Commission for Racial Equality to investigate whether black and ethnic-minority doctors were unfairly treated. He said they filled 70 per cent of the middle-ranking, non-consultant grade posts and were being held back when hospitals were crying out for consultants.

He said: "The NHS is desperately short of consultants yet there are plenty of doctors capable of working at consultant level.But many of these doctors are shunted into staff grades and are prevented from even trying to become consultants.

"These doctors are overwhelmingly from ethnic minorities. This is part of the racism in the health service that is totally unacceptable."

In response, the Secretary of State for Health said: "We are looking at ways of changing the law so that more overseas qualifications can count towards completion of UK training for doctors.

He added: "Just as there is racism in some parts of British society, we think that there is probably racism in some parts of the NHS. We treat that very, very seriously indeed, and have made it very clear to employers in the NHS that they have got to take action on this issue."

A report in the summer by the King's Fund, an independent think-tank, said that racism was "a daily fact of life" for doctors who were trained abroad. The report suggested they were sidelined within British medicine and lost out on the best jobs.