Japan's population has grown so little since last year that an exodus of travelers abroad during the holiday season in May triggered the first-ever fall in the country's year-on-year monthly population, according to government data obtained this week.

The final estimated population on May 1 was down 50,000 from a year earlier to 127.56 million, marking the first decrease since the government began compiling monthly population counts in 1950, according to the Internal Affairs and Communications Ministry.

Under the ministry's calculations, travelers who leave Japan for overseas sightseeing trips are also counted as having moved abroad and are thus deducted from the total population.

"The total population on May 1 last year was big because of a sharp reduction in travelers going overseas due to the SARS epidemic" in other parts of Asia, the ministry said. "Compared with that, (the population this May) has shrunk, but this is just a temporary phenomenon."

Yet analysts said the fact that a fluctuation in the number of overseas travelers can sway the direction of population growth shows that Japan may soon experience a population decline.

The monthly estimated population is calculated by adding or subtracting such factors as the number of births and deaths, as well as people going in and out of Japan, to the latest national census, which is conducted every five years.

In an average year, the number of Japanese traveling abroad increases around late April to early May during the Golden Week holiday season.