Prime Minister Shinzo Abe may have known of the veterinary school project at the center of favoritism allegations against him roughly two years earlier than he has stated, a document obtained by Kyodo News showed Monday.

The revelation prompted opposition parties to redouble their criticism of Abe, who is under fire for allegedly using his influence to sway the approval process that led to the opening of Japan's first veterinary department in half a century by Kake Gakuen (Kake Educational Institution) last month.

Kotaro Kake, who heads the school entity, is a longtime friend of Abe. But the prime minister has repeatedly denied involvement in the approval process for the project, which is in a special deregulation zone in Imabari, Ehime Prefecture.