Peaches Geldof will escape drugs charges because of a legal loophole, police said last night.

Officers have seized footage of the 19-year-old apparently paying for drugs but are unlikely to be able to convict her because they cannot prove what she bought.

She is due to be questioned by detectives within days.

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On film: Peaches Geldof on a secretly-shot video taken as part of a Scotland Yard investigation into the supply of drugs to stars

They will not say if she will be arrested or interviewed under caution.

The TV presenter was filmed handing an alleged drug dealer up to £190, telling him: "I'm going to need Valium tomorrow after this."

Valium can be used to come down after taking stimulants such as cocaine, Ecstasy and amphetamines. Possession of any of them can lead to jail.

The secretly-shot film was found on a PC memory stick taken from Jonny Blagrove and Cara Burton as part of a Scotland Yard investigation into the supply of drugs to stars.

On the same video is footage of Amy Winehouse allegedly smoking crack at a party, which made headlines in January.

Sources confirmed the police are focusing on gathering sufficient evidence against the alleged pushers.

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Peaches Geldof is set to escape charges after police admit that they cannot prove she was buying drugs in secret footage

One said: "At present, there is no prospect of Peaches being charged with criminal offences. However, she could end up being a vital witness."

Model Kate Moss escaped charges two years ago after she was filmed snorting a substance because police could not prove it was drugs.

The failure to prosecute her was condemned by politicians and drugs campaigners.

Now a similar row is looming over Peaches, the daughter of rock singer and Band Aid organiser Bob Geldof.

He has already said he would go "ballistic" if she went off the rails.

Her mother, Paula Yates, died at 41 from a heroin overdose in 2000.

The footage of Peaches begins with Blagrove and Burton driving to a meeting with the teenager.

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Peaches parents: The late Paula Yates and Bob Geldof, before their divorce

The camera microphone picks up the couple talking to Peaches, who is clutching £140. Then Blagrove tells her the deal will cost £190.

She is seen agreeing to this and then telling the couple she will need Valium the next day.

The video was taken the day before Blagrove filmed Winehouse in a set-up at her home.

Police believe Blagrove and his girlfriend wanted to set Peaches up in the same way.

The footage had been deleted from the memory stick but detectives were able to use special techniques to find it.

They were also able to recover a further two hours of footage of Winehouse.

When Blagrove and Burton were arrested, police found a long list of names and numbers of their alleged celebrity clients at their home in East London.

The couple were bailed pending further questioning by police.

Peaches denied rumours that she took drugs after apparently being pictured using a 'bullet', a device which can be used to inhale cocaine, in April 2006.