The home secretary is permanently lifting restrictions placed on police in the use of stop and search powers.

Priti Patel announced the changes in a letter to police forces on Monday, under Section 60 of the Criminal Justice and Public Order Act, saying they are part of the government’s strategy to tackle violent crime.

The law gives police officers the right to search people without reasonable grounds when serious violence is expected.

The changes extend the length of time the powers can be in force from 15 hours to 24 hours, and they can be extended to 48 hours instead of the previous 39 hours.

They also mean that the use of the powers can be authorised by an inspectors rather than the previous senior office, while a superintendent can no extend the length of time the powers are in force.

Officers authorising the powers now only need to anticipate that serious violence “may” occur, whereas previously they had to anticipate that this level of violence “will” occur, and they no longer have to inform communities in advance.

The laws are controversial due to concerns that they are used disproportionately against black and other minority groups.

In the year to March 2021, black people were seven times more likely to be stopped and searched than white people, while Asian people were two-and-a-half times more likely.

A recent report by the Independent Office for Police Conduct called for an overhaul in the use of these powers for this reason.

Ms Patel said: “The devastating impact of knife crime on families who have lost their loved one is unbearable.

“No one should have to endure the pain and suffering of the victims of these appalling crimes and we have a responsibility to them to do everything in our power to prevent future tragedies.”

She said use of stop and search has increased by around 85% since 2019 and some 50,000 weapons have been taken off the streets.

“I stand wholeheartedly behind the police so that they can build on their work to drive down knife crime by making it easier for officers to use these powers to seize more weapons, arrest more suspects and save more lives.”