A decision on whether to reclassify cannabis as a more serious drug will be taken in the next few days, Home Secretary Charles Clarke has said.
Cannabis was downgraded to class C two years ago
He told BBC Radio 4's Today programme he was "worried" about new studies linking it with mental health problems.
Cannabis was downgraded from class B to class C two years ago, but Mr Clarke ordered a review of that last year and said the move had confused the public.
Experts and charities are divided over the drug's possible reclassification.
Dame Ruth Runciman, who chaired the initial inquiry that recommended downgrading cannabis, said reclassification would confuse the public even more.
"I think it is very ill-judged thing to do and that it actually puts cannabis where it does not belong in the scale of relative harm," she said.
But John Henry, a clinical toxicologist at St Mary's Hospital in London, told BBC News there was a "strong link" between cannabis and schizophrenia.
"It's probably about four times commoner in people who smoke cannabis regularly," he said.
The drug was downgraded under Mr Clarke's predecessor, David Blunkett.
The maximum penalty for dealing in a class B drug is 14 years in jail, while class C dealing carries a maximum of five years.
It was hoped downgrading cannabis would allow the police to focus on tackling harder drugs like heroin and crack.
"Since that decision, further medical evidence has been developed about the implications of consumption of cannabis on mental health, which is serious," Mr Clarke told Today.
Last March he asked the advisory group to consider the issue again in the light of the latest research.
Its report has been presented to the home secretary but not yet made public.
"The fact is we still don't know a lot about that relationship [with mental health], as the advisory committee report makes clear, but what we do know is concerning," Mr Clarke said.
He told the Times newspaper the committee had strongly recommended a "renewed commitment to public education" about the potential effects of the drug.
He said the downgrading had led to public confusion and promised action to alert people to its dangers.
Shadow home secretary David Davis said he welcomed the recognition that "there is new evidence about the dangers of cannabis, particularly with regard to mental health".
Liberal Democrat home affairs spokesman Mark Oaten said the government should not base drug policy on "tabloid pressure".
"The case for treating drugs in different categories remains very strong and unless the advisory body make a strong argument to change this, the government should resist reclassification."
On Wednesday, health charity Rethink urged Mr Clarke to look at the mental health risks of cannabis rather than "fiddle with its legal status".
It called on him in a letter to devote resources to reducing the risks of the drug.