SEOUL (Kyodo) South Korea has begun work to renovate a heliport on the disputed Takeshima islets in an effort to reinforce its control amid Japan's repeated sovereignty claims, Yonhap news agency reported Thursday, citing a South Korean government source.

"It is difficult to make a public announcement on this, given the issue's sensitivity, but the heliport repair work has already been launched and is quietly under way," the source was quoted as saying.

"This measure is to strengthen our effective control in response to Japan's bolstering of territorial claims over Dokdo," the source said, using the Korean name for the islets.