Marina Certo, 41, of Arlington Avenue, Lillington, had pleaded guilty at Warwick Crown Court to three charges of supplying heroin to the officer, believing he was a fellow addict.

She also admitted being concerned in the supply of heroin and crack cocaine and was jailed for three years.

Prosecutor Matthew Brook said that in May last year 'Craig', an undercover officer in Operation Laser, was on a bench in Christchurch Gardens, Leamington, when Certo approached him and told him she was suffering from heroin withdrawal symptoms and had no money.

Certo told Craig of a dealer call Brownie, who sold £30 bags of heroin, but she did not have his number on her.

They met at the park again two days later and Certo brought Brownie's number and used Craig's mobile telephone to call it.

As they waited for dealer David Brown, who is yet to be sentenced, to turn up, Certo told Craig she had bought drugs from him earlier that day.

And when the dealer arrived Certo handed him £30 she had been given by the undercover officer in exchange for a wrap of heroin, which she gave to Craig.

To maintain his cover, Craig gave Certo a small amount of the heroin for arranging the deal.

On the day in between, Certo had carried out another 'pass the parcel supply' to Craig, said Mr Brook.

The had again met in the park, where she mentioned a dealer called D, saying she did not have a number for him but knew someone who did.

They went to find that person in the town centre and he made a call to dealer Katie Reynolds for them.

A meeting was arranged at the Eagle Street recreation ground where Reynolds, who has been jailed for six years, handed a £10 wrap of heroin to Certo who gave it to Craig.

At the end of May Craig called Certo saying he wanted some heroin and she told him of another dealer, Nicholas Grainger, who she said sold 'heavy bags'.

She used Craig's telephone to call Grainger, who has been jailed for three years, and they went to his home at Ashton Court, Lillington.

Certo went into the flat and bought a £10 wrap of heroin from Grainger's girlfriend to give to Craig.

In June Craig asked Certo about crack cocaine and she volunteered that her son-in-law Thomas Johnstone, who also lived at Ashton Court, would be able to supply both crack and heroin.

Certo told Craig to go to the block of flats and call her.

When he did Johnstone, who has been jailed for six years, came out to his car and supplied him with wraps of heroin and crack.

Mr Brook said that when Certo was arrested she said she believed she had been helping a fellow addict.

Andrew Molloy, for Certo, asked for her to be given full credit for her guilty pleas, adding that the only question was how long her prison sentence would be.

Jailing Certo, Judge Marten Coates said: "Although your name has cropped up with monotonous regularity over the last few weeks, the part you played is at the lowest end of the scale."