British businesses must take action to tackle a so called "class pay gap", the government's social mobility czar warned on Thursday (26 January).

Alan Milburn issued the call after finding that professional from working-class background earn an annual average of £6,800 ($8,567) less than their colleagues from more affluent upbringings.

The former Labour minister said many employers are doing "excellent work" to open their doors to people from all backgrounds, but argued that more needed to be done to ensure everyone has an equal chance.

"How much you are paid should be determined by your ability, not your background," Milburn added.

"Employers need to take action to end the shocking class earnings penalty. The Commission will be sending major employers details of this research and asking them how they intend to close the class pay gap."

Academics from the London Schools and Economics and University College London used the 90,000-strong Labour Force Survey to conduct the research.

The report, among other things, found that Britain's traditional professions such as medicine, law, journalism and academia remain "dominated" by those from advantaged backgrounds. Almost three quarters (73%) of doctors are from professional and managerial backgrounds with fewer than 6% from working class backgrounds.

The study also discovered the biggest "class pay gaps" exist in finance (£13,713), medicine (£10,218) and IT (£4,736).

"While social mobility represents the norm, not the exception, in contemporary Britain, there is no doubt that strong barriers to opportunity still persist," said Dr Sam Friedman, an assistant sociology professor at the LSE.

"By capitalising on new socio-economic background questions in the UK Labour Force Survey, we have been able to shine a light on some of the most pressing, but largely unexplored issues in British society today.

"In particular, we have found evidence of a powerful and largely unacknowledged pay gap within the professions. There are a number of reasons for his such as higher educational attainment among the privileged. But even when these factors are taken into account, this gap remains significant."

A government spokesperson said: "We are looking at ways to deliver more good school places in more parts of the country, investing in improving careers education, transforming the quality of further and technical education and opening up access to our world–class higher education system.

"Through our Industrial Strategy we are determined to close the wealth gap between regions, improve living standards and create jobs so everyone can share the benefits of our economic success.

"The government is also targeting social mobility 'coldspots' with 12 'Opportunity Areas' where we are working with local organisations, schools, colleges, and businesses to overcome barriers to social mobility and make sure young people from all backgrounds can go as far as their talents will take them."