Unions are set to launch a grievance procedure against airport operator BAA in a bid to tackle the complaints, which include accusations of workers being forced to work longer hours, not being able to take breaks and bullying by senior staff.

Security staff today told the News how morale was at rock-bottom because of increased pressure in the face of tough new rules on passengers carrying hand luggage and liquids.

BAA today said it took any allegations of bullying seriously but had yet to receive any official complaint.

But one member of the airport's security team, who asked not to be named, said: "It is really bad. Some supervisors and management are just treating the staff like dirt.

"We have voted for the grievance procedure but feelings are really strong on this and I would say that people would strike over it if it carries on.

"They seem to be more interested in punishing people and trying to catch you out on the smallest of things rather than improving the security.

"There is so much pressure on you to spot liquids that people are worried that some of the newer staff might spot the bottle of water in a bag but might miss the knife next to it."

In 2006 Diane Scullion, a former security manager at the airport, was awarded £6000 compensation by an employment tribunal after a row over alleged bullying and harassment.

Miss Scullion refused to accept the complaint she had made against three senior staff at Edinburgh Airport in 2002 had been rejected and was eventually sacked before taking the case to a tribunal

, which found her dismissal had not followed proper procedures.

In 1996, six airport security guards were suspended amid allegations they were bullying temporary staff for taking all the available overtime.

Sandy Smart, regional industrial organiser of the Transport and General section of the Unite union, said: "There is a lot of ill-feeling among the staff at the airport. It is an operational issue and is something we are trying to resolve through a grievance procedure.

"We had an similar issue a few years ago and that was sorted out, but it seems to be back.

"There is a lot of pressure on the security staff these days. It is a difficult job, and over the summer season Edinburgh Airport is extremely busy. It is early days in terms of what will happen, but I am confident it is something we can address by getting round the table with BAA."

An Edinburgh Airport spokeswoman said: "We take any allegation of bullying or harassment from our staff extremely seriously and thoroughly investigate any complaint. However, we have received no such official complaint."