The father, who runs a medication distribution company, sat a test for a licence to handle over-the-counter drugs so that his son could work with him, said an official in Nara prefecture in western Japan.

An examiner noticed that the man looked unusually old, said local government official Masaaki Nakamori.

'A 20-year-old and a 54-year-old are aged differently. But he looked like the photo on the exam admission card,' Mr Nakamori said.

The father, whose name was not released, earned his own licence last year, taking the exam with a photo showing him with straight hair and glasses.

'This time, he curled his hair and did not wear his glasses,' Mr Nakamori said.

The man put his face down intently near the desk as he took the exam, he said.

'When the test monitor approached him, he admitted it and apologised. He said, from the application process to actual testing, he did it all himself without telling his son,' Mr Nakamori said. -- AFP