The government is being urged to hold urgent talks over the future of Royal Mail after claims of a concerted bid to "run down" the industry.
Postal workers accused of "skiving" and "stealing"
The Communications Workers Union (CWU) has written to Trade and Industry Secretary Patricia Hewitt complaining of attempts to "smear" postal workers.
It follows attacks on Royal Mail over pricing policy and single deliveries.
Fresh claims of staff laziness, fraud, ineptitude and theft are to be aired in a Channel 4 programme on Thursday.
CWU deputy secretary general Dave Ward said the mail industry was a "mass" of competing interests, pulling in opposite directions and "getting nowhere".
He said: "We have a government which fails to accept accountability for an
industry it owns.
"We have the regulator, Postcomm, which sees its primary role as
driving and encouraging competition by allowing private firms into the industry
without any regard for our universal service obligation.
"We have the consumer watchdog Post Watch, which constantly attacks the
business in a negative way."
High profile business leaders appointed to run the Royal Mail
were pursuing their own agendas, Mr Ward said.
"We cannot continue to have an industry directed by four competing factions,
with a fifth - CWU representing the workforce - with the most to lose."
In a letter to its branches, the CWU said there had been a series of major attacks on Royal Mail in the past week, including complaints about the new single deliveries and new pricing policies.
"The union is concerned that what we are witnessing is part of a coordinated
attack designed to undermine the public's faith in our postal service and raise
questions about its trustworthiness, its value and ultimately its ownership,"
the letter said.
The latest allegations, in Channel 4's Dispatches programme, are being trailed as a "shocking expose" of habits and attitudes within the industry.
The Royal Mail's pricing policies have come under fire
A programme spokesman said one of its reporters went under-cover to reveal a "damning" catalogue of skiving workers, ineffective managers and gangs of criminals
stealing millions of pounds from the post.
A spokesman for the Department of Trade and Industry said the department took its responsibility as a Royal Mail shareholder "seriously" but it did not intend to hold crisis talks.
"The CWU was one of the parties that campaigned hard for the commercial
freedom this government gave Royal Mail so it could act more like a commercial
company," the spokesman said.
"One consequence of that is that when things go wrong the management and
workforce must work together to put things right."
He added that the Dispatches programme had made "a number of serious allegations" but that ministers could not comment on them until they had viewed all the material.
It was a criminal offence to steal, tamper with or delay mail and the Royal Mail proceeded such cases "vigorously" with police, it added.