By Tim Bradshaw in Cannes

Twitter is looking at introducing advertisements among the short messages that users see in the most active part of the social networking service, according to people with direct knowledge of its plans.

The move comes as Twitter looks at options to generate revenues from a service that has so far failed to make money from its audience as well as rivals such as Facebook.

The move to place ?promoted tweets? in the main ?stream? of tweets on the service is likely to be controversial with users who have seen only limited marketing messages so far in Twitter?s five-year history.

Other commercial options under discussion include deals and offers similar in style to rival Groupon which aggregates consumer demand for time-limited specific offers. It is also looking at introducing enhanced profile pages for brands and media management tools, which could allow advertisers to pre-schedule 140-character posts.

Twitter executives including Adam Bain, head of revenue, have been meeting with marketers on the fringes of the Cannes Lions event this week to discuss new ways of harnessing its 300m registered users for advertising.

Twitter introduced promoted tweets, its first advertising products, last year. Modelled on Google?s search advertising system, promoted tweets appear when users type relevant terms into Twitter?s search facility.

It also now offers ?promoted trends? at the top of the list of the most popular topics of discussion on the site, and ?promoted accounts? in a list of recommended users to follow.

Although some brands have had success with these formats, Twitter is looking for something which can offer greater scale.

According to three people familiar with the situation, Twitter?s plans would see promoted tweets appear in their main timeline, the main focus of the Twitter website. Twitter had tested such ads with a third-party mobile client, HootSuite.

Users could see tweets from a brand they follow appear high up in their stream even if they were posted hours before. A ?quickbar? in Twitter?s iPhone software which prominently displayed promoted trends in the timeline prompted a user uproar earlier this year, forcing Twitter to remove the feature.

Twitter said: ?We are always talking with marketers about ways they could potentially get more out of Twitter. Some of these discussed concepts may materialise; others will not.?

? The Financial Times Limited 2011