The number of prisoners in England and Wales has reached a record high.
The previous record high was reached on 29 June
Official figures suggest there were 81,135 people locked up in jails and in police stations on 27 September.
This exceeds the previous record of 81,040 inmates reached at the end of June, when the government's emergency early release scheme came into effect.
There is still some capacity remaining in the system, but the Ministry of Justice said it was the highest official total ever published.
The BBC's home affairs correspondent Danny Shaw said prison governors were said to be "beginning to get worried" about prison capacity.
'Waste of money'
A spokeswoman for the Ministry of Justice said of the total, 80,803 were held in prisons and 332 in police cells.
Given the total prison capacity of 81,915, there remain 780 spaces available to house new criminals, she added.
The ministry went on to defend the government's record, saying more prison places were being built to off-set overcrowding.
It said since Labour came into power in 1997, there were 20,000 more places - 3,100 of which were built in the last two years.
Lucie Russell, director of SmartJustice, said Gordon Brown must "get to grips" with the problem by expanding community punishments and making prison an option only "for those who really need to be there".
"Prisons are full up with the mentally ill and drug addicts for whom it is mainly an expensive way of making them worse," Ms Russell said.
"With nearly three-quarters of offenders reconvicted within two years of leaving prison at a cost of £50,000 per person per year, this just isn't an effective use of taxpayers' money."
Liberal Democrat justice spokesman David Heath described the government's management of prisons as "a mixture of incompetence and panic measures".
It needed to ensure "those that should not be in prison are put where they can be provided with real treatment in secure mental institutions or drug rehabilitation centres", he said.
"Unless the government is serious about breaking the cycle of reoffending, in which prisons act increasingly as a revolving door for repeat offenders, our overburdened prison system will remain under severe strain and we will not be able to cut crime," he added.
Separate figures published on Friday show that following the introduction of the emergency prisoner release scheme, 6,325 offenders had been released by the end of August.
That includes about 900 prisoners convicted of robbery or violence.
There are currently 48 prisoners still at large who were released, but should have been sent back to prison for breaching their conditions or re-offending.