The operator of a tour bus that crashed into an expressway wall in late April in Gunma Prefecture denied Sunday that the company's violation of regulations in its daily operations caused the fatal accident.

Yumihide Hariu, 55, president of the firm Rikuentai based in Chiba Prefecture, told a press conference in Tokyo that he believes the crash occurred as Kazan Kono, a 43-year-old tour bus driver arrested over the accident, had dozed off.

The Land, Infrastructure, Transport and Tourism Ministry has said Rikuentai employed Kono on a day-work basis in violation of the road transport law and failed to provide instructions detailing routes and scheduled stops to its drivers as required by the government.