The Tories have promised to back 'have-a-go' heroes who intervene when they see crimes being committed on the streets.

Shadow home secretary Dominic Grieve outlined proposals to reverse the current "perverse approach to law enforcement" at the party's conference in Birmingham.

He said: "It's our duty to help, not hinder active citizens. We'll scrap the Whitehall targets that encourage police to pick on soft targets.

"We'll amend the police guidelines so officers back those who use reasonable force to maintain the Queen's peace.

"And we'll ensure that the code for Crown Prosecutors is amended so it is crystal clear that it is not in the 'public interest' to prosecute those who perform a citizen's arrest in good faith."

His call came after a banker was beaten to death after helping a homeless man who was assaulted in Norwich city centre on Sunday.

Mr Grieve also announced plans to free police from health and safety red tape, warning it was "holding" officers back and making them more "risk-averse".

He said the regime was "so stifling that it delayed armed officers attending the victims of a shooting an hour after the gunman had fled" while allowing others to be prosecuted for "mistakes made during the heat of a counter-terrorism operation".

A Conservative government will change health and safety rules applying to the police, he promised, during a thinly attended debate.

"We don't want to put officers at unnecessary risk. But public protection must come first," he said.

"We will change the laws to support our brave officers and make the public safer."

Mr Grieve also confirmed Conservative plans to return 500 officers to the beat by slashing police paperwork.

"A Conservative government will get itself out of the police's way by cutting targets and consolidating the excessive police audit arrangements which led to one force undergoing 15 different inspections in a year.

"We'll back officers not hold them back."

He promised greater power for sergeants to authorise stop and search and to give custody sergeants charging discretion for all summary offences - insisting this could free up another 500 officers for patrol.

Accusing the Government of "dropping the ball" on security and radicalisation, Mr Grieve vowed there would be "zero tolerance" of those who incited violence against the country under the Tories.

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