By Alison Smith
BBC News education reporter, at the ATL conference
Independent Schools Council dismissed the claims
Up to 30 independent schools have closed or are due to close in the coming months because of the economic climate, a teaching union has said.
And the number of private schools making redundancies was "running into hundreds", the Association of Teachers and Lecturers (ATL) claimed.
The ATL said some schools had no redundancy policy and the closures had exposed managerial weaknesses.
The Independent Schools Council said it was "absurd" to talk of any crisis.
The claim of 30 closures includes 17 schools which have already closed or will close by the end of this year.
The rest disappeared through mergers with other schools, or by becoming academies, according to ATL, which has 20,000 members working in private schools.
At their annual conference, ATL passed a motion pledging to "campaign vigorously to ensure all independent schools have a long-term strategic plan to avoid closure, and where this is not possible, due process to ensure that the employer's obligations to staff are met."
Schools which expanded rapidly during the good times may not have planned for a downturn, members said.
Malcolm St John Smith, who proposed the motion, said some schools did not even have basic employment procedures in place.
The union's concern at the lack of financial planning by some independent schools pre-dated the recession, he added.
He called for independent schools to be submitted to an inspection regime which included contingency plans and financial planning.
"A robust test of fitness should be applied. More needs to be done on a regulatory level," he said.
He mentioned one independent school which was shut when its owner flew in on a helicopter, spoke to staff, and then flew out again.
But it would be wrong to think that all independent schools failed to plan effectively, he said.
It is thought there are around 2,500 independent schools in England, so the closures would represent roughly 1% of the sector.
John Richardson, ATL's national official for independent schools, said some were particularly affected where pupils' parents worked in financial industries or where families living in coastal areas had been affected by the downturn in tourism.
"A redundancy policy is the minimum you would expect as it gives clarity in a difficult situation," he said.
"The government has said nobody should get less than the statutory minimum, but we'd expect good employers to pay more."
Statutory redundancy is one week's wages for every year of service, if the employee is below the age of 40, whereupon it rises to one and a half week's pay.
Mr Richardson said ATL would be campaigning for independent schools to set a good example, and said that they "ought to be treating their staff better".
Independent Schools Council chief executive David Lyscom said the ATL's reports were "misleading and unhelpful".
"There is always some churn at the margins in the independent schools sector and this year is no exception," he said.
"ISC data shows that since May 2008, although 20 schools left ISC associations, 11 joined.
"If ATL were to be successful in undermining confidence in independent schools, it is its own members who will suffer from redundancies."
He added that evidence gathered by the ISC suggested the independent school sector had not been affected by the recession in the same way as other sectors of the economy.