Overcrowding in UK prisons has reached breaking point and could lead to widespread riots, according to the Prison Officers Association (POA).
The assocation has accused the government of ignoring warnings that about 60 percent of British prisons ahave breached their official maximum capacity.
POA chairman Peter McParlin said the problem would escalate by the summer and prisons could explode.
"How the government decides to deal with that crisis is going to be extremely interesting," he told Sky News. "We've been in conversations with them in which we've asked them to reopen mothballed prisons - prisons that were at the cutting edge of the rehabilitation revolution - but they are refusing to do that."
"The number of prison officers we have will be inadequate to cope with riot situations in our prisons and if we continue as we are - warehousing prisoners, not being able to build the relationships between prisoners and prison officers that have been successful in the past - we will see riots in our prisons in which we will not be able to cope."
Experts fear the number of inmates in England and Wales could hit the maximum of 89,463 later this year.
Labour MP Ian Austin suggested that Justice Secretary Ken Clarke should send British prisoners to Poland and other eastern European countries to ease pressure on overcrowded jails in the UK.
The idea was based on a similar policy followed in the Netherlands, which agreed to house 500 inmates from Belgium in a £26m-a-year deal.