A rising number of soldiers do not have recommended rest periods

More than half "often think about quitting", and 38% blamed "operational commitment and overstretch".

Responses came from 2,306 soldiers, 42% officers, between March and July 2006. Most were based in the UK, but 102 were in Iraq and three in Afghanistan.

The MoD said job satisfaction among soldiers had never been higher.

A rising number of soldiers are no longer given the full recommended rest periods between operations.

And only 30% of the ordinary soldiers who responded to the survey were satisfied with the notice given for extra duties.

Unfair treatment

Almost three out of every five rated their workload high or very high.

Only 31% felt "valued", and nearly one out of every four - 23% - said their morale was low or very low.

The same proportion expressed fears they were not doing the job for which they were trained - but 71% continued to "enjoy" the job.

The survey also revealed dissatisfaction with the way the Army deals with complaints about bullying, harassment, discrimination and other unfair treatment.

Of the 27% who had made complaints, less than one out of every four were happy at the way they were handled, with 17% calling Army discipline "unfair".

'High morale'

Military chiefs say troops are stretched but deny any "overstretch".

An MoD spokeswoman told BBC News the survey indicated morale was higher than it had been during the same period last year.

Most respondents had said they had "high" or "very high" morale and were satisfied with their equipment, she added.

While 64% of soldiers had said they were "fairly satisfied" or "very satisfied" with their job - more than ever before.