Staff at Birmingham City Council have been banned from using work computers for online gambling.

Nor must they play any games, unless they are taking part in a business-related training course.

Participating in chat rooms is also prohibited, unless there is a legitimate business need.

And officials who are authorised to contribute to a professional online forum have been told to refrain from expressing political or personal views, and to stick to agreed council policy, taking care to "maintain the consistency and integrity" of the corporate message.

The restrictions are in a new internet code of practice covering the local authority's 50,000 employees.

Workers have been told they can use the internet for their own purposes during lunch breaks, but only if their line manager approves. All usage is monitored by the IT d epartment and a number of "inappropriate" sites have been blocked, including those featuring pornography and violence.

The code warns: "Private use is a privilege. Birmingham City Council may withdraw private use at any time if this interferes with council business."

Staff are also warned of excessive internet usage and told not to download large files at busy times.

The code demands all internet use must be conducted in an honest, legal and businesslike way and s taff must behave decently and appropriately.

It goes on: "You must not make personal, hurtful or derogatory remarks. In particular, you must not distribute defamatory material. Messages on the internet can reach large numbers of people and defamatory s tatements can do substantial damage."

Although the council has had an internet use policy in place since 1996, the previous version was found to have "a number of shortcomings" following an audit review.