The number of prisoners in England and Wales has reached a new record, the Prison Service has said.
Numbers have been rising for two months
There were 73,091 inmates by Wednesday - compared with the previous record on 25 October last year of 73,033.
Numbers fell before Christmas but have been rising for the last two months with only 500 spare places left.
The jail population has risen by 170 in eight days meaning if the numbers continue to rise at the same rated the system could reach "bust point" in less than three weeks.
Prison reform campaigners are calling on the government to tackle the rising numbers blaming overcrowding for high rates of reoffending by offenders and suicides among inmates.
But the Prison Service says work is already underway to reduce overcrowding as part of the wider reform of the criminal justice system.
The government is uncompromising in insisting prisons should be reserved for the most dangerous and persistent offenders
Juliet Lyon, director of the Prison Reform Trust, said the government faces a "stark choice" at a time when the proportion of people jailed in England and Wales is the highest in western Europe.
She said: "Government can reserve prison for serious and violent offenders only, and rebalance the criminal justice system towards punishment in the community.
"Alternatively it can allow prisons to become overcrowded social dustbins, and face appalling reconviction rates and a rising toll of suicides as a result."
A Prison Service spokesman said the government would continue to provide places for those sentenced by the courts.
"The government is uncompromising in insisting prisons should be reserved for the most dangerous and persistent offenders," he told BBC News Online.
Nearly 1400 extra prison places had been created with further investment promised over three years, he told BBC News Online.
Funding is in place to increase the total number of places to 77,200 by March 2006, he said.
Home Office estimates have predicted the prison population could reach 110,000 within six years.
New initiatives are already in place as part of a three-year strategy to reduce rates of suicide and self harm.
Efforts are being particularly focused on "high risk" areas, such as remand and the first few weeks of custody when prisoners were adapting to their new environment.
"The prison population is very, very vulnerable. Very often they are victims of abuse and neglect outside", he said.
Last month it was suggested prisoners were harming themselves in jail at a rate three times higher than previously thought.
The Howard League for Penal Reform argued that more than 21,000 prisoners harmed themselves in custody every year as it argued for overcrowding to be dealt with.
But the Home Office said the large increase had been due to changes in the criteria for reporting self-harm.
Full and part-time suicide prevention officers are being funded as part of the three-year strategy.
England and Wales have the European Union's highest imprisonment rate of 139 per 100,000 of population.
Ten years ago the average figure for the prison population was just 44,566.