The study of 43 police forces in England and Wales - compiled from Home Office statistics - also found that murders of black people only result in identification of a suspect 60% of the time, compared to 90% for a white victim.

And in a sample of 10 forces, independent civil liberties monitoring body Statewatch found black suspects were between four and seven times more likely to be sentenced to prison terms.

'Nothing but a PR exercise'

They are also more likely to serve longer prison terms than their white counterparts.

A spokesman for Statewatch said: "It confirms that British police forces are institutionally racist and that the situation is ongoing despite police promises to the country.

The Stephen Lawrence inquiry: Severe criticism

"Their measures to address racism have been little more than a PR exercise. Absolutely nothing has changed."

The survey is likely to add to pressure for police reform following the branding last month of the Metropolitan police as "institutionally racist".

The allegation was made in a damning report into police handling of the murder of black teenager Stephen Lawrence.

Norfolk 'worst'

Among the most significant findings of the study were the widely differing applications of stop and search procedures by different forces - particularly in terms of race.

The average rate in England and Wales for black people stands at 142 per 1000, compared to 45 for Asians and 19 for whites.

Cleveland topped the list, with more than 40% of the black population subject to stop and searches. Merseyside was second with up to a third.

Cautions 'less likely'

Dorset and Essex were at the bottom of the table, with a rate of four and six per thousand heads of population respectively.

The Norfolk force was found to be the most likely to arrest black people, having taken in 857 from an approximate population of 1,400 - around 60%.

The authors acknowledge that this result is likely to be a distortion. However, they have confirmed that all other figures are reliable and broadly in line with their findings last year.

Merseyside and Staffordshire forces came next with approximately a third of their black populations arrested.