Indonesia said Wednesday it rejected China's claims over a disputed part of the South China Sea as "having no legal basis," after two days earlier protesting to Beijing over the presence of a Chinese coast guard vessel in its territorial waters.

The boat trespassed into Indonesia's exclusive economic zone off the coast of the northern islands of Natuna, leading Indonesians officials to issue a "strong protest" and summon the Chinese ambassador in Jakarta.

Speaking in Beijing on Tuesday, Chinese Foreign Ministry spokesman Geng Shuang had said China has sovereignty over the Spratly Islands and their waters and that both China and Indonesia have "normal" fishing activities there.