Police are making unjustified searches of members of the public to provide "racial balance" to stop and search statistics, it was revealed today.
Lord Carlile, the independent reviewer of terror laws, said he knew of cases where suspects were stopped by officers even though there was no evidence against them.
He warned that police were wasting money by carrying out "self-evidently unmerited searches" which were an invasion of civil liberties and "almost certainly unlawful".
Lord Carlile, a Liberal Democrat peer and QC, condemned the wrongful use of Section 44 of the Terrorism Act 2000 in his annual report on anti-terror laws.
He said police were carrying out the searches on people they had no basis for suspecting so they could avoid accusations of prejudice.
As the terror threat against Britain is largely from Islamist extremists, the figures show disproportionately more Muslims and therefore more Asians being searched than whites.
But the peer said police should stop trying to balance the figures, and it may be that an "ethnic imbalance" is a "proportional consequence" of policing.
He wrote: "I have evidence of cases where the person stopped is so obviously far from any known terrorism profile that, realistically, there is not the slightest possibility of him/her being a terrorist, and no other feature to justify the stop.
"In one situation the basis of the stops was numerical only, which is almost certainly unlawful and in no way an intelligent use of the procedure.
"I believe it is totally wrong for any person to be stopped in order to produce a racial balance in the Section 44 statistics. There is ample anecdotal evidence this is happening.
"I can well understand the concerns of the police that they should be free from allegations of prejudice, but it is not a good use of precious resources if they waste them on self-evidently unmerited searches.
"It is also an invasion of the civil liberties of the person who has been stopped, simply to 'balance' the statistics.
"The criteria for section 44 stops should be objectively based, irrespective of racial considerations: if an objective basis happens to produce an ethnic imbalance, that may have to be regarded as a proportional consequence of operational policing."
Figures released earlier this year revealed a huge increase in searches using Section 44 powers.
Officers in England and Wales used the powers to search 124,687 people in 2007/8, up from 41,924 in 2006/7 and only 1% of searches led to an arrest.
Nearly 90% of the searches were carried out by the Metropolitan Police which recorded a 266% increase in its use of the power.
Officers in London use Section 44 to carry out stop and search between 8,000 and 10,000 times a month.
Lord Carlile questioned why Section 44 powers are thought to be needed in some areas but not in others facing similar levels of risk.
He criticised the Metropolitan Police for not limiting Section 44 use to parts of London, and said the number of searches being carried out by the force was "alarming".
He said: "I cannot see a justification for the whole of the Greater London area being covered permanently, and the intention of the section was not to place London under permanent special search powers.
"The figures, and a little analysis of them, show that section 44 is being used as an instrument to aid non-terrorism policing on some occasions, and this is unacceptable."
He added "I repeat my mantra that terrorism-related powers should be used only for terrorism-related purposes; otherwise their credibility is severely damaged."
Lord Carlile said the use of Section 44 had an "undoubtedly negative" impact on community relations.
He added: "I am sure it could safely be used far less. There is little or no evidence that the use of Section 44 has the potential to prevent an act of terrorism as compared with other statutory powers of stop and search."
After the publication of stop and search figures earlier this year, the Met announced it was reviewing its use of Section 44, and in future it would be restricted to policing "iconic" or strategically important sites.
A Home Office spokesman defended the use of the powers. He said: "Stop and search under the Terrorism Act 2000 is an important tool in the on-going fight against terrorism.
"As part of a structured anti-terrorist strategy, the powers help to deter terrorist activity by creating a hostile environment for would-be terrorists to operate.
"Countering the terrorist threat and ensuring good community relations are interdependent and we are continuing to work with the police to ensure that the use of stop and search powers strikes the right balance."