BREAKING: Drugs stash worth up to Â£1MILLION seized in Sheffield police raids

Supt Simon Wanless briefing officers on Operation Duxford this morning

Police have estimated the value of the substance- which appears to be heroin although testing has not yet confirmed this- to be at least £500,000.

This estimate is based on the substance being prepared for street dealing but depending on the purity police said the value could be up to £1million.

The force made 12 arrests and recovered many illicit items from four warrants carried out in the Burngreave area of Sheffield as part of Operation Duxford.

BREAKING: Eleven arrests in three hours as police launch huge operation in Sheff...

The intelligence-led operation began early this morning and will continue late into the night.

Temporary Superintendent Simon Wanless said: "It's been better than we could have hoped."

He added: "Should we not be doing this all the time? Yes we should, and we will. For me it's an element of making this day to day activity and not a special occasion."

Operation Duxford is set to ahead in Doncaster, Rotherham and Barnsley in the next three months, returning to Sheffield in March.