Black people are 26 times more likely than white people to be stopped and searched by police in England and Wales, the most glaring example of "racial profiling" researchers have seen, according to an international report.

The analysis of government data has brought claims of discrimination from campaigners who say the findings corroborate concerns that black and Asian Britons are being unfairly targeted. The US civil rights activist Jesse Jackson, who arrives in London today to launch a campaign aimed at curbing what he says is stop-and-search discrimination, described the figures as "astonishing".

The figures relate to stop-and-searches under Section 60 of the Criminal Justice and Public Order Act 1994, which was introduced to deal with football hooligans and the threat of serious violence. It allows police to search anyone in a designated area without specific grounds for suspicion.

Analysis by the London School of Economics and the Open Society Justice Initiative found that there are 41.6 Section 60 searches for every 1,000 black people, compared with 1.6 for every 1,000 white people – making black people 26.6 times more likely to be stopped and searched. Asians were 6.3 times more likely to be stopped than whites, according to the analysis of Ministry of Justice figures for 2008-09.

The data reveal a marked escalation in relative searches of ethnic minorities in England and Wales. In the previous year blacks were 10.7 times more likely to be stopped than whites, and Asians 2.2 times more likely. Ben Bowling, professor of criminal justice at King's College London, said: "The police are making greater use of a power that was only ever meant to be used in exceptional circumstances and lacks effective safeguards. This leaves room for increased stereotyping which is likely to alienate those communities which are most affected".

His concerns are exacerbated by new draft Home Office guidance which will allow police to stop and search on the basis of ethnic origin under Section 60, a development which critics say raises the prospect of a return to the contentious "sus" laws of the 1980s. Tomorrow a new campaign group called Stopwatch will ask the government to abandon the use of stop-and-search powers that do not require reasonable suspicion, such as Section 60 powers.

Researchers at the Open Society Justice Initiative, part of the Open Society Foundation supported by billionaire financier George Soros, said the British figures provided the widest "race gap" in stop-and-search that they had found internationally. The previous highest use of stop-and-search powers against ethnic groups was on the Moscow Metro, where non-Slavs are 21.8 times more likely to be stopped by Russian police than Slavs. A study on the Paris Metro found passengers of Arab appearance were more than seven times more likely to be stopped. The practice has caused disquiet in New York where blacks and Hispanics are nine times more likely to be stopped than white New Yorkers.

Dr Rebekah Delsol of the Open Society Justice Initiative said that even factoring in slight differences in methodology and data gathering, the international comparison revealed "staggeringly high" levels of what she claimed was racial profiling among British police using Section 60.

Dr Michael Shiner, of the Mannheim Centre for Criminology at LSE, said additional safeguards are necessary and the government should provide explicit guidance so that everyone is clear where action is needed. "What is interesting is the rapidness of the change," he said. "Year-on-year you would ordinarily not see much of a difference, but this is a staggering increase of disproportionality at a time when there is a massive increase in the use of Section 60."

Shiner and Bowling said the use of the stop-and-search power would increase tension and damage confidence in the police. Use of Section 60 has risen more than 300% between 2005 and last year amid concerns among campaigners that it is being abused as a "catch-all" power in response to low-level disorder. In 1997/98 there were 7,970 stop-and-searches, increasing to 53,250 in 2007/08 and 149,955 in 2008/09. Between 2005/06 and 2008/09 the LSE found the number of Section 60 searches of black people rose by more than 650%.

In July, home secretary Theresa May announced that police use of Section 44 counter-terrorism stop-and-search powers, which allowed officers to act without reasonable suspicion, was to be curtailed immediately following a decision from the European Court of Human Rights.

However, campaigners say that Section 60 should also be repealed. Other stop-and-search powers, Section One of the Police and Criminal Evidence Act, require officers to have reasonable suspicion for a stop search. Under Section One, black people are seven times more likely to be stopped than white people.

The figures coincide with plans to weaken the way stop-and-searches are recorded by police forces. Draft Home Office documents, seen by the Observer, reveal that future recording will be so heavily weakened that repeat stops of the same person will no longer be recorded. They also open the way for officers to search someone under Section 60 on the basis of ethnicity. Although Home Office guidance states care must be taken not to discriminate against ethnic minority groups, it says there are times when officers should "take account of an individual's ethnic origin in selecting persons and vehicles to be stopped".

Delsol added: "The revisions still open the way for ethnic profiling and the stopping of large numbers of innocent people from ethnic minority backgrounds just because they happen to be in an area defined for a Section 60 search zone."

A spokesman for the Home Office said that under their new proposals ethnicity could not be used as the sole basis for stopping anyone under Section 60, with the new guidance "intended to protect civil liberties".