A leading lawyer has warned Teletext and Thomas Cook that rival firms are likely to continue to try to use their brand names despite threats of legal action.

Google lifted a ban last week on firms bidding to use trademarked names to improve the Google ranking of their ads.

And in a revolutionary move, Thomas Cook has already terminated the contracts of five partners – travel agents or affiliates – who have bid on brand names associated with Thomas Cook.

Intellectual property partner Adrian Smith from law firm Simmons and Simmons said the outcome of any court case in this area was uncertain.

“There is no doubt people will continue to try it on until there is a definite ruling whether this is legitimate or not.

“I’m not surprised the big names in the industry are concerned about this. It is hard enough to protect your brand online as it is, but Google appears to have made life a bit easier for the infringers.”

A Thomas Cook spokesman said: “Parties advertising on our brands where they neither have access to, nor sell our products, are misleading the consumer, and any activities along these lines are a clear breach of trademark law.

“All travel agents, partners and affiliates that are contracted to promote and/or sell our products and services are not allowed, under our contractual agreements, to bid on any of our brand terms.”

Teletext said a number of major travel companies, which had been bidding on “teletext” for most of last week, curtailed their campaigns within hours of the legal threat.

Teletext managing director Matt Cheevers said: “We have taken the stance not to bid against any of our competitor brands and we will not tolerate any company that we find to be bidding against our name. Companies that do not stop this activity instantly will be dealt with by our solicitors.”