Suspected dealers who swallow drugs to hide them from police could face X-rays or ultrasounds to detect them, under measures unveiled on Friday.
Selling fresh mushrooms will be outlawed under the new measures
The Home Office's new Drugs Bill would also bring tougher penalties for those caught dealing drugs near a school or using children as couriers.
The bill also includes a crackdown on the sale of fresh magic mushrooms.
Drugs Minister Caroline Flint said the measures would get "more people off drugs and away from crime".
Under the proposals, an X-ray or ultrasound could take place when a suspect gives written permission.
However, if a suspect refused to undergo a scan it would count against them in court.
Ms Flint said: "The Drugs Bill will introduce further powers for police to drug-test suspected addicts on arrest so our drug intervention programme can get more people off drugs and away from crime.
"Dealers will face harsher sentences when they prey on children or attempt to escape justice by swallowing the evidence."
'Unsavoury and degrading'
In other measures included in the bill:
- Those suspected of swallowing drugs would be allowed to be held in custody for eight days so the drugs can pass through their system
- Police will get powers to test suspects for some Class A drugs before they are charged with an offence
- People caught with a greater amount of drugs than considered reasonable for personal use would be presumed to be dealers and face tougher sentences
- A drug intervention order would be introduced to run alongside anti-social behaviour orders, if drug abuse had been a cause of the Asbo being applied
Shami Chakrabarti, director of civil rights group Liberty, said: "The proposal on X-rays is intrusive and coercive.
"We doubt the medical profession would want to be involved in such unsavoury and degrading practices."
But Dr Michael Wilks, chairman of the British Medical Association ethics committee, said he was satisfied by the provision that the procedure would only be performed after consent had been given.
He added that X-rays would not necessarily find all packages that had been swallowed.
The Home Office said X-rays were already used by Customs officers to identify smugglers.
The law concerning magic mushrooms, a Class A drug, has not been updated for 30 years.
Recent months have seen a number of shops openly selling the drug as unprocessed mushrooms.
"There is a need to clarify the law so that it's completely clear that fresh magic mushrooms as well as dried are illegal, to clamp down on some cases where magic mushrooms have been sold openly," the Home Office spokeswoman said.
Social care charities DrugScope and Turning Point say the bill focuses too heavily on forcing people into unsuitable treatment programmes.
Turning Point's chief executive Lord Adebowale said: "People are complex and you can't expect them to overcome dependency if they're still struggling to find a house or don't have the support they need to get back into work."
The Tories and Liberal Democrats said the bill contained "positive" measures, but said more needed to be done to target dealers and help users.