Moves to scale back the most widely drawn counter-terrorism powers left in the police "stop and search" armoury have been initiated by the home secretary, Theresa May.

An official consultation was launched on Thursday on the future of random "stop and detain" powers, which have been used by police special branch officers to question 70,000 travellers a year going through Britain's airports and ports.

The move follows criticism from the government's own official terror laws watchdog and within Muslim communities that people from an Asian background are 42 times more likely than white people to be targeted for these random counter-terrorism interrogations.

The national security powers, introduced under schedule 7 of the Terrorism Act 2000, allow the police and immigration officers to detain any airline, ferry or train traveller for up to nine hours to determine if they are involved in terrorism.

People can be targeted by special branch under the powers without the need for reasonable suspicion that they are involved in any crime. Those who are stopped currently have fewer rights than suspects detained at a police station; they have no access to publicly funded legal advice and failure to answer questions is a criminal offence. They can also be strip-searched and have intimate DNA samples taken from their body.

David Anderson, the official reviewer of terrorism legislation, has highlighted the negative impact of these powers on some Muslim communities, with many of those stopped feeling they were targeted as Muslims in order to build up a profile of Muslim communities. He has described their effect as "bubbling under the surface … eroding trust".

The Home Office consultation document published on Thursday shows that the numbers stopped under the powers have dipped in the last few years from 87,218 in 2009-10 to 69,109 in 2011-2012. The latest figures also show that 60% of those stopped are from a minority ethnic background, with 29% Asian or British Asian. This proportion rises to 45% of those who were detained. A further 47% of those detained were from a black, Chinese or other non-white background. Only 8% of those detained were white.

A total of 2,240 people were examined for more than an hour under these powers in the last year, of whom 681 were detained, nearly all of whom had DNA samples taken. In the last three years Home Office figures show that 2.8% or about 6,440 people have been examined for more than an hour, with 42 of them held for more than six hours.

The consultation says the options being considered include reducing the legal nine-hour detention limit, introducing a "reasonable suspicion" test, increasing the rights to legal advice, limiting the use of strip-searches and repealing the power to take intimate DNA samples.

The Home Office says use of these powers directly led to about 20 prosecutions a year for terrorist-related offences between 2005 and 2009 and that a number of key individuals had been convicted as a result of a port stop.

The home secretary said the use of these schedule 7 counter-terrorism powers formed an essential part of Britain's border security arrangements helping to protect the public from those travelling across borders to plan, finance, train for and commit terrorism.

"Examining people at ports and airports is necessary to protect public safety, but we want to ensure these powers are used proportionately, and are effective. This consultation seeks the views of the public to help ensure we get this right," said May.

Corinna Ferguson, legal officer for the civil liberties campaigning group Liberty, said: "This review is welcome but limited and long overdue. Like discredited stop and search powers, schedule 7 doesn't require suspicion of wrongdoing, but even worse – allows people to be detained for nine hours and have their DNA taken and property seized. Most have been non-white, causing understandable community resentment. The court of human rights will soon hear Liberty's case challenging this power – so the Home Office may have to go much further than it has today."