Prime Minister Junichiro Koizumi remained vague Friday on whether a suspected North Korean spy boat had entered Japan's exclusive economic zone in the Sea of Japan before its sighting was made public Wednesday.

"We cannot say clearly" whether the boat was in the economic zone before being spotted, Koizumi told reporters at his office. The government said Wednesday the boat was outside Japan's EEZ when it was first sighted.

Transport minister Chikage Ogi said she was informed that the boat was outside Japan's EEZ when it was spotted, while Chief Cabinet Secretary Yasuo Fukuda said he believes the boat had not entered the EEZ even before Wednesday's announcement.