Retrospective changes to the government's Highly Skilled Migrant Programme (HSMP) were criticised by MPs and recruiters.

Parliament's joint committee on human rights met on 9 August to discuss the changes made to the legislation last November.

Estimates of the number of migrants affected by the changes vary from 6,000 to 49,000.

John Davison, managing director of Europeople, which recruits workers across a number of sectors including engineering and industrial, says that the changes were unfair.

Davison told Recruiter: "It's moving the goalposts in the middle of the game and a number of people are going to be caught out."

Davison's concerns were echoed by Anne Fairweather, external relations manager at the REC.

Fairweather asked: "If these migrant workers were valuable four years ago when they came into the country, why are they not valuable now?"

The HSMP was introduced in 2002 to attract "the brightest and the best" migrant workers.

It is a points-based system with points awarded for age, qualifications, last 12 months' earnings and work experience in the UK.

The rules were changed back in November, making it harder for migrant workers to get a visa by raising the number of points needed to meet the criteria from 65 to 75 and being more stringent on the number of points allocated per category.