Tokyo - Thousands of Japanese Thursday congratulated Emperor Akihito on the 20th anniversary of his accession to the throne.

At an official ceremony in Tokyo's National Theatre Prime Minister Yukio Hatoyama passed on his government's congratulations.

The 75-year-old monarch became emperor on January 7, 1989, after the death of his father Hirohito.

Following a period of mourning for his father, Akihito was officially crowned as Japan's 125th emperor on November 12, 1990 in the Imperial Palace in central Tokyo.

Emperor Akihito is the first Japanese emperor not to be considered divine.

His father, controversial for his role in the World War II, renounced the emperor's divinity in a declaration on January 1, 1946.

The post-war constitution stripped the emperor of his political powers and limited his role to symbolising the unity of the nation. (dpa)