SEOUL (AFP) - South Korea on Friday carried out a military exercise aimed at repelling any attempted landing on a tiny set of islets also claimed by Japan.

The four-hour exercise involving five warships, jet fighters and helicopters, demonstrated "the military's will to defend" the Dokdo islets, a defence ministry spokesman said.

The South Korea-controlled Dokdo islets, known as Takeshima in Japan, have been the subject of a bitter and decades-old territorial dispute between the two countries.

The exercise came as South Korea celebrated Dokdo Day, which was designated four years ago in an effort to promote South Korea's sovereignty.

Japan reacted angrily to the military drill, with Chief Cabinet Secretary Yoshihide Suga calling it "extremely regrettable".

"We have lodged a strong protest with the South Korean side in Tokyo and Seoul through diplomatic channels," Mr Suga said, stressing that the islets were an "integral" part of Japanese territory.

South Koreans view Tokyo's claim as a reflection of Japan's failure to atone for its repressive 1910-1945 colonial rule over their country.