Media playback is unsupported on your device Media caption The BBC's Chris Buckler went to meet some ketamine users living in a squat in Bristol, who told him about the health problems they had experienced

The number of people using the drug ketamine increased significantly over the last decade in the UK, while its price fell, a report has said.

The Independent Scientific Committee on Drugs cited surveys that in 2009 found some 68% of UK clubbers had taken the drug, compared with 25% in 2001.

The committee is calling on ministers to offer more help for users and raise awareness of potential health problems.

Ketamine use can cause bladder problems as well as kidney and liver damage.

The committee said that ketamine's classification in the lowest Class C category of controlled substance wrongly suggested it was less dangerous than ecstasy (Class A) or cannabis (Class B).

"Our review of the scientific evidence suggests that this classification of ketamine does not accurately reflect its known and potentially severe harms," the report said.

But the ISCD specifically does not call for ketamine to be reclassified.

"All our research suggests that changing classification does not change people's use of the drug," said Professor Val Curran, who co-wrote the report.

"Ketamine was originally just controlled under the Medicines Act.

Jim Bartlett, Bristol Drugs Project If you have urinary tract, bladder or kidney pain tell your GP that you use ketamine and ask for a referral to your local urology department. Try to stop or reduce your use if these symptoms start. If you experience K cramps, don't sit in the bath to soothe the pain; there is a risk of unconsciousness and drowning. Tolerance develops quickly to ketamine, meaning you may need higher doses to get the same effect. Keep your use as low as possible and take breaks if you can. Plan ahead if you want to stop using and get help from professionals and friends. Gradual reduction may be easier than just stopping - but always ask your doctor first.

"When it was made a Class C under the Misuse of Drugs Act its use went up and its cost came down."

The report added that an annual survey had found the average price of a gram of ketamine had fallen from £30 to £20 between 2005 and 2008 - and since become cheaper still.

'Very dangerous'

Some campaigners are calling for ketamine's classification to be changed.

Shielmor Twomey insists that ketamine was a significant factor in the death of her son Caleb, who killed himself in Bristol last year.

"I looked it up on the internet to see if it was a harmful drug," Mrs Twomey said.

"Having seen it was a Class C, I thought it's not going to do him any harm.

"The government should realise that it's a very dangerous drug and it needs to be reclassified."

Ketamine is an animal tranquiliser but its use as a recreational drug has grown over the last decade.

The British Crime Survey began including the drug in 2006, and reported an increase in users from about 85,000 in 2006/07 to 113,000 in 2008/09.

Bristol is one of the cities where ketamine has become increasingly popular.

"It's showing its face in more mainstream club culture," according to Jim Bartlett of the Bristol Drugs Project.

"We have seen increasing numbers of people coming to us with ketamine-related problems."

Image caption The parents of Londoner Louise Cattell launched a campaign after she drowned having taken ketamine

Deaths

Several of the users at the project say they have suffered serious stomach cramps and the bladder infection cystitis.

"When I went to the toilet I started getting blobs of blood," said one woman who had to have a serious operation on her bladder at the age of 18.

"Your bladder starts shrinking.

"If I knew this would do this to me when I was that young I wouldn't have done it."

The report says that, aside from the potential physical and neurological damage, there is a concern about people having serious accidents.

Most of the small but growing number of deaths linked to ketamine have been caused by the users not being fully aware of their surroundings.

The review says they include people who have drowned and died from hypothermia.