The prison population in England and Wales has exceeded its highest normal level for the first time.

The Ministry of Justice said that as of Friday morning there were 82,068 inmates in jails - 96 over the Prison Service's "operational capacity".

Justice Secretary Jack Straw has asked magistrates to jail fewer people while officials attempt to manage the crisis.

Some 358 inmates are in police or court cells to ease pressure on a system with current capacity of 81,972.

Ministry of Justice figures reveal that the population breached that capacity on Thursday evening.

The breach comes despite a year of efforts to reduce pressures by releasing more prisoners and building more cells.

The figures mean that for the first time the Prison Service has almost 100 more inmates in jail than the numbers governors want to hold to ensure a controlled and secure regime.

The total is also 8,000 higher than the Prison Service's own assessment of what would comprise a "good, decent standard of accommodation" in uncrowded conditions.

There are still 2,000 additional spaces above operational capacity - but these are not normally used because of constraints, including where beds become available and the need to keep dangerous prisoners separate.

A spokesman for the Ministry of Justice said that it took its responsibilities towards the safety and security of prisoners "extremely seriously".

"No prison will be expected to operate at a level of crowding beyond that certified by the Prison Service area manager (or regional offender manager in the case of a contracted prison).

"As far as possible we do not hold vulnerable prisoners in police cells under Operation Safeguard. This includes prisoners identified as being current risk of suicide or self-harm."

He added that while prisons were operating above "useable operational capacity", that did not mean prisons were "entirely full" and it was possible to use some places within the "operating margin".

The prison population has risen dramatically since Christmas, outstripping the number of new places becoming available. Key factors in the rise include more inmates on short sentences for less serious offences.

Justice Secretary Jack Straw has now called on 350 magistrates courts to use community punishments because they were proven to be more likely to cut re-offending.

But Cindy Barnett, the chairman of the Magistrates Association, warned it would be "very unfortunate" if ministers tried to pressurise the courts over the sentences they handed down.

"I think it is incredibly important that in each individual case, whether it is a judge or a magistrate, the sentencer makes up their mind as to what is the most appropriate sentence," she told the BBC.

"We are incredibly aware of the pressures on prison places at the moment. We don't use custody lightly, we use it when it is so serious that nothing else can be justified and we must make that individual decision."

Shadow Justice Secretary Nick Herbert said prisons were in genuine crisis.

"Contrary to what Jack Straw implies, this is not the fault of magistrates, but the result of sheer incompetence by this government.

"They have ignored repeated warnings that cells were needed, failed to build adequate capacity, and their belated prison building programme has fallen behind schedule."

Colin Moses of the Prison Officers' Association also condemned the Ministry of Justice, accusing it of "total mismanagement".

He told the BBC: "The prisons are not safe. We have now increased the numbers yet again with no change in regime and no increase in staffing.

"This is now risk management at the highest level. The government's policy towards prisons is like boiling a kettle - there is a red line and when you fill it with water, you don't cross that line.

"But if you start crossing that red line little by little, the kettle will eventually boil over. The question is when."

Government are asking courts not to send anyone else to prison