Calls have been made by the Prison Governors Association for some inmates to be released early with electronic tags to ease jail overcrowding in England and Wales.
The government is considering early release as 'one option'
But campaigners say sentencing and the causes of crime are the real issues which need to be tackled.
William Higham, of the Prison Reform Trust, said despite fewer people being found guilty by the courts, more people were being sent to jail.
"It is not a crime wave we are seeing, but a punishment wave," he said.
He pointed to Home Office figures showing people found guilty at a crown court had fallen by 3,612 to 1,733,016 between 1993 and 2003.
But at the same time, there had been "dramatic rises" in the number of people sent to prison by magistrates.
He said Home Office figures showed that 19.6% of people sentenced to theft from shops, the most frequent offence tried, received an immediate custodial sentence in 2003, compared with 2.6% in 1993.
Mr Higham, the trust's head of policy and communications, said: "Politicians must realise that 'talking tough' on crime constantly leads to more people in prison and puts more pressure on prisons trying to reduce re-offending."
Trust director Juliet Lyon added the home secretary "must keep his commitment to reserve prison for serious and violent offenders".
"Solutions lie in cutting any unnecessary remands and recalls to custody, using fines and supervised community sentences and diverting addicts and the mentally ill into the treatment they need," she said.
Home Office figures show that in 1993, there were 44,246 people in jails and police cells in England and Wales, but by 1997 the number had risen to 61,467 and by 2003 to 73,657.
According to the World Prison Populations List, in 2003 the US had 701 people in jail for every 100,000 of the national population - the highest rate in the world.
In comparison, the UK's prison rate was 141 per 100,000 of its population, placing it mid-way in the World List, but highest among EU countries.
Lucie Russell, director of campaign group Smart Justice, said: "Not enough is being done to tackle the causes of crime and because the media is punitive, especially the tabloids, it puts pressure on the politicians and the sentencers."
Smart Justice campaigns for and promotes projects to prevent crime, tackle the causes of crime and find alternatives to custody for "low-level" offences such as shoplifting and car theft.
Among solutions it favours include "drug treatment orders" where courts oversee a drug addict's rehabilitation.
Ms Russell said: "We believe a lot of people in prison shouldn't be there because it is not effective at reducing their offending behaviour."
She said more than half of adults and three-quarters of young offenders were reconvicted within two years of being released.
"Prisons are a university of crime," she said. "People go in knowing how to do one crime and come out knowing how to do four others."
She said people who committed low-level offences included many who had been in care, over half of offenders had mental health issues and "at least three-quarters" had drug problems.
Ms Russell said the female prison population alone had almost tripled in the last 10 years with women now seven times more likely to be jailed by magistrates' courts than in 1991.
She said in most cases these women were being locked up for non-violent offences.
The Home Office said there was "no single factor" behind the increase in the prison population, but sentencing had been made tougher.
Since 1993, the number of magistrates' court cases resulting in custody had increased from 6% to 16%, and from 49% to 60% in the crown courts, a spokeswoman said.
She said the enforcement of community sentencing had been increased by the Probation Service, with the percentage of people being recalled to prison rising from about 45% in 2001 to 90% this year.
"We have made sentences tougher for serious and violent offenders and make no apology for that," she said.
The spokeswoman added the government also recognised "balance was needed" and it sought to punish more low-level crimes by means such as home detention curfews that enabled people to stay in the community.