The AA has been reviewing the performance of patrols

The union said patrol staff had been sent a letter saying most were very committed to the AA and its members, but a few workers were falling short.

Staff who meet expectations will get �2,000 in recognition of their work, but those below standard will be offered �18,000 voluntary severance.

The AA denied the GMB's claims, saying a maximum of 20 jobs would go.

The AA was bought by venture capital firms CVC Partners and Permira from Centrica for �1.75bn ($3.13bn) in July 2004.

GMB official Paul Maloney said: "The venture capitalists currently running the AA are seeking to force 431 patrol staff out of a job and they are trying to do it in the most underhand way.

"They are trying to bribe employees with money and are asking them to sign confidentiality agreements in return for giving up their jobs."

'Minority fall short'

The GMB says it represents about half the patrol staff at the AA, with the other half members of an in-house union.

The AA said it had been reviewing the performance of patrols, as part of an "ongoing business transformation".

"The review, carried out with full union consultation, has identified that whilst the majority of patrols meet or exceed the company's expectations, a minority fall short of achieving the required performance levels," it said in a statement.

"There are also a very small number of individuals who are potentially redundant due to low workload in their geographical area."

An improved package of measures was available for patrols performing well and a comprehensive package was in place for those leaving the company, the AA added.