Black Britons and those of south Asian origin face “shocking” discrimination in the labour market at levels unchanged since the late 1960s, research has found.

A study by experts based at the Centre for Social Investigation at Nuffield College, University of Oxford, found applicants from minority ethnic backgrounds had to send 80% more applications to get a positive response from an employer than a white person of British origin.

A linked study by the same researchers, comparing their results with similar field experiments dating back to 1969, found discrimination against black Britons and those of south Asian origin – particularly Pakistanis – unchanged over almost 50 years.

The research, part of a larger cross-national project funded by the European Union and shared exclusively with the Guardian before its official launch, prompted concerns that race relations legislation had failed.

Racial bias in Britain – what it feels like | Kamran Ahmed and others Read more

It echoes findings published as part of the Guardian’s Bias in Britain series that people from minority ethnic backgrounds face discrimination when seeking a room to rent. In a snapshot survey of online flatshare ads the Guardian found that an applicant called Muhammad was significantly less likely to receive a positive response than an applicant called David.

Prof Anthony Heath, co-author and emeritus fellow of Nuffield College, said: “The absence of any real decline in discrimination against black British and people of Pakistani background is a disturbing finding, which calls into question the effectiveness of previous policies. Ethnic inequality remains a burning injustice and there needs to be a radical rethink about how to tackle it.”

The researchers sent almost 3,200 applications to both manual and non-manual jobs – including software engineers, marketing, chefs and shop assistants – advertised on a popular recruitment platform between November 2016 and December 2017.

The study, which will be launched at the British Academy, London, on Friday, included 33 different minority ethnic groups, belonging to five broad groups. Additionally, two minority ethnic groups – Nigerian and Pakistani – were designed to have sufficiently large numbers of applications for separate analysis. Different ethnicity applicants were randomly assigned to different job vacancies – only one application was sent per post – and the number of callbacks/invitations for interview compared.

On average, 24% of applicants of white British origin received a positive response from employers, compared with 15% of minority ethnic applicants applying with identical CVs and cover letters. All of the minority applications clearly stated that they were either British-born or had arrived in the country by the age of six and had obtained all their education and training in Britain.

Minority ethnic applicants, including white minorities, had to send 60% more applications to get a positive response from an employer than a white person of British origin. While applicants originating from western Europe and the US were treated almost as well as the majority group, people of Pakistani origin had to make 70% more applications. The figures were even higher for those of Nigerian, Middle Eastern and north African (MENA) origin, at 80% and 90% respectively.

Dr Zubaida Haque, the deputy director of the race equality thinktank Runnymede, described the findings as shocking. They demonstrated that “it’s not just covert racism or unconscious bias that we need to worry about; it’s overt and conscious racism, where applicants are getting shortlisted on the basis of their ethnicity and/or name”, she said.

“It’s clear that race relations legislation is not sufficient to hold employers to account. There are no real consequences for employers of racially discriminating in subtle ways, but for BME applicants or employees it means higher unemployment, lower wages, poorer conditions and less security in work and life.”

The researchers said the high levels of discrimination from countries with a sizeable Muslim population echoed “strong anti-Muslim attitudes recorded in recent surveys”.

Dr Valentina Di Stasio, co-author and an assistant professor at Utrecht University, the Netherlands, said: “The persistent gaps in callbacks found for more visible and culturally distant minorities, regardless of the occupation considered or the information included in the application, suggest that employers may simply read no further as soon as they see a Middle East-sounding or African-sounding name.”

As past field experiments did not include people from MENA countries, it could not be ascertained whether the level of discrimination against them had changed over time. Additionally, the historical comparison could only be done for non-manual jobs, due to insufficient past data on manual jobs.

Nevertheless, the authors described the evidence of enduring discrimination against some minority ethnic groups as striking given the passage of the Race Relations Act 1976 and that many of the earlier studies included applicants born abroad with some foreign education.

They said that while surveys had found declining racial prejudice among the public, the lack of change in the workplace reflected the continued presence of “employer stereotypes about the linguistic and work-related skills and motivations of minorities”.

There were hints that discrimination against applicants of Indian origin may be in decline but the researchers said the sample size of people with Indian names in their study was too small to draw firm conclusions.

Responding to the results, Matthew Fell of the Confederation of British Industry said: “Any bias is bad for business. Companies must act now to eradicate all forms of discrimination, including any bias in recruitment.”

A spokesperson for the Department for Business, Energy and Industrial Strategy also stressed the benefits of diversity, adding: “Last year, the prime minister launched a series of measures to help employers identify how to tackle ethnic disparities in the workplace, including a new race at work charter and a consultation on mandatory ethnicity pay reporting.”