Operation Evolve targeted alleged street dealers in response to a " serious drugs" problem in the county countering the scourge of heroin, cocaine and crack cocaine.

A total of 24 properties in Dalkeith, Bonnyrigg, Loanhead, Penicuik, Mayfield, Newtongrange, Gorebridge, Pathhead and two in Edinburgh were hit by early morning raids on Tuesday and Wednesday last week.

On day one of the £100,000 operation, 18 people were arrested while on day two a further 15 people were detained. All have appeared at Edinburgh Sheriff Court where four were remanded in custody.

The blitz, which took 15 months to plan, recovered more than £5000 in cash, cocaine with a street value of £700, £2000 worth of heroin, a hydroponics system and cannabis plants, alleged stolen property and other drug related paraphernalia.

E Division Commander Chief Superintendent Terry Powell told the Advertiser: "Most places have a serious drugs problem and Midlothian is one of many areas. It is no different from Edinburgh.

"There is no doubt about that and what we found in the 15 months of investigation was that getting class A drugs was easily available and this was particularly so in Dalkeith, Mayfield and Bonnyrigg."

He added that by using "imaginative evidence gathering" the secretive operation, involving 100 officers drafted in from all areas of the force, all the alleged targets were arrested.

"We are over the moon," said CS Powell of the operation. "It is unprecedented that we got 100 per cent on both days and got a couple of extra in the net who happened to be in the right place and the wrong time for them."

Operation Evolve was a multi-agency initiative involving Midlothian Council and health professionals to provide support to drugs users and their families afterwards.

"We brought in health partners early on for that and also to get some sort of outreach work established to support drugs abusers in the community so there was an holistic approach," added CS Powell.