A welfare ministry official who was arrested on suspicion of accepting a ¥1 million ($8,360) bribe in connection with the My Number social security and tax number system may have accepted several million yen more from the same person, investigative sources said Wednesday.

Kazuyuki Nakayasu, 45, with the Ministry of Health, Labor and Welfare, was arrested Tuesday for allegedly taking the cash bribe from a former executive of a Tokyo-based information technology company in November 2011 for assisting the firm in winning two computer system development contracts worth a total of ¥210 million for the introduction of the My Number system.

The suspect has admitted to the bribery charge of ¥1 million, saying, "I demanded it," a police official said.