China on Tuesday expressed its "strong dissatisfaction" over an Indian leader's visit to a disputed border region.

"China is strongly dissatisfied with the visit to the disputed region by the Indian leader disregarding China's serious concerns," said Chinese Foreign Ministry spokesman Ma Zhaoxu.

Ma said China and India had never officially settled demarcation of their border, and China's stance on the eastern section of the China-India border was consistent and clear-cut.

"We demand the Indian side address China's serious concerns and not trigger disturbance in the disputed region so as to facilitate the healthy development of China-India relations," Ma said.

Indian media reports said Prime Minister Manmohan Singh toured and addressed an election rally in the so-called "Arunachal Pradesh".