SCOTLAND'S most senior police officers have warned that plans for a new single force could damage evidence gathering and forensics.

Chief constables and superintendents fear the legislation currently going through Parliament may interfere with the policing of crime scenes as forensic gathering will be carried out by an independent body and not by the officer in charge of the case.

They have also expressed concern that the changes could affect the operational independence of the new chief constable.

Scotland's eight police forces will be rolled into one and the new single police service will begin on April 1, 2013.

The bill, which proposes making forensic services independent from policing, is now being scrutinised by the parliamentary justice committee.

The independent system in England and Wales has been much criticised in recent years.

The submission by the Association of Scottish Police Superintendents (ASPS) to the committee states: "In our opinion, responsibility for operational direction and control of staff at crime scenes should be a matter for the police alone. This will ensure appropriate levels of service at crime scenes under the control and direction of senior investigating officers, whose role it is to oversee all elements of evidence gathering."

Both ASPS and the Association of Chief Police Officers in Scotland (Acpos) have also warned the current phrasing in the bill would interfere with the operational independence of the new chief constable because it says the minister could "direct" them.

The Acpos submission called for forensic services proposals to be "re-examined".

A Scottish Government spokesman said there was wide support for the proposals and added: "The reform legislation proposes maintaining the integrated forensic science service – including scenes of crime."

On the independence of the chief constable, the spokesman said: "The bill improves accountability for policing and is absolutely clear that the chief constable is accountable to the Scottish Police Authority, not ministers."