US regulators are reviewing Twitter\'s dealings with firms that build applications and services for the popular messaging service, according to published reports. The Wall Street Journal, citing a \"person familiar with the matter,\" said the Federal Trade Commission (FTC) is reviewing Twitter\'s interactions with UberMedia, a company that build programs using Twitter data. The newspaper said the precise focus of the review is not clear but it was \"narrow\" in scope and would not impact Twitter\'s advertising business. Twitter and UberMedia were rival bidders earlier this year for TweetDeck, a company that designs tools for using Twitter. Twitter eventually won out and bought TweetDeck. UberMedia and TweetDeck are among the scores of companies that have developed applications for using Twitter. Twitter recently has been creating rival services of its own and it briefly banned UberMedia earlier this year from access to the stream of messages known as tweets. The website Business Insider, which first reported the FTC inquiry, quoted an UberMedia representative as saying the company has been \"contacted by the FTC and are in the process of responding to their requests.\" The Journal noted that the FTC routinely looks into companies to determine whether they are involved in anticompetitive behavior and the reviews often do not result in any legal action. Contacted by AFP, both the FTC and Twitter said they had no comment on the reports.