Popular microblogging site Twitter is all set to unveil its advertisement model on Tuesday, which would mark its first step toward allaying concerns about its revenue generating potential.

The advertising program known as Promoted Tweets will be rolled out to two to 10 percent of users via search on Twitter.com beginning Tuesday, company spokesperson Sean Garrett told Reuters.

Promoted Tweets are ordinary tweets that businesses and organizations want to highlight to a wider group of users, Garrett said.

Users will start to see tweets promoted by our partner advertisers called out at the top of some Twitter.com search results pages, he added.

Several companies will run ads, including Best Buy, Virgin America and Starbucks, the New York Times said on its website.

The 2-1/2-year-old Internet start-up's short text messages or tweets have become a global social phenomenon and the service is used by millions of people every day.

Twitter has great potential as a marketing and advertising channel with opportunities to create viral buzz around a product or service, said Eden Zoller, analyst at technology research firm Ovum.

The flip side of Twitter's immediacy is that if advertising messages are not very carefully positioned users can hit back at brands and in real time, and brands will have little control over this.

Twitter, a privately held company, does not report earnings, but its website says: While our business model is in a research phase, we spend more money than we make.

(Reporting by Shrutika Verma in Bangalore, Alexei Oreskovic in San Francisco and Georgina Prodhan in London; editing by Simon Jessop)