A former employee of Novartis Pharma KK, the Japan unit of the Swiss drugmaker, has been arrested on suspicion of manipulating data to promote the company's best-selling blood pressure drug Diovan.

Nobuo Shiraishi is suspected of violating Japan's pharmaceutical laws by providing false data to researchers, whose work was intended for use in advertising the drug, the Tokyo District Public Prosecutor's Office said in a statement.

Novartis Pharma KK said it would cooperate with the investigation.

Anyone found guilty of exaggerated advertising of drugs in Japan can be punished with up to two years in prison or a fine of as much as 2 million yen ($19,600), or both.