American financial regulators are reportedly threatening to sue the boss of Mexican broadcasting giant TV Azteca for fraud.

The Securities and Exchange Commission, say insiders, has warned Azteca -- the world's second-largest Spanish-language TV firm -- to answer fraud allegations involving chairman Ricardo Salinas Pliego or face a federal lawsuit in the US.

At the heart of the dispute is a debt deal involving Azteca and two firms controlled by Pliego. The SEC, which can take an interest in the case because Azteca's shares are traded in New York, is expected to claim this agreement harmed the broadcaster's shareholders.

Under the deal, Mexican telecoms firm Unefon, which Pliego controls, sold its $325 million (€261m; £178m) debts to a group called Codisco for $107m. Azteca then paid off the $325m in full, leaving Codisco with a profit of $218m.

Last month it emerged that Pliego indirectly controls 50% of Codisco, with the remainder owned by businessman Moises Saba. However, the Azteca boss claims he did not hold this stake at the time of the deal.

Several private suits have already been filed against Azteca over the transaction. The broadcaster, however, has promised to fight the accusations.

Data sourced from: Financial Times; additional content by WARC staff