Online auction firm eBay has introduced tighter rules for the use of its discussion boards.

It is now not permissible to use the boards to warn other members about poor experiences with another buyer or seller.

There is also a ban on asking for advice on where to buy a particular item, and sharing private email addresses is also a violation of the terms and conditions.

Should an offending post be removed by eBay, members are not allowed to discuss it on the board. Anyone violating the rules can be banned from eBay's services, and they too instantly become an off-limits topic for discussion.

A number of recent lawsuits in the US have tested the liability of sites similar to eBay for defamatory content found in chat rooms. This increase in litigation may be behind the decision.