BEIJING, China - China on Tuesday expressed anger over a recent visit by Indian Prime Minister Manmohan Singh to a border region at the core of a long-standing dispute between the neighbours.

"China is strongly dissatisfied with the visit to the disputed region by the Indian leader, who disregarded China's serious concerns," Chinese foreign ministry spokesman Ma Zhaoxu said in a statement.

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

Singh visited Arunachal Pradesh on October 3 to campaign ahead of state elections, but refrained from saying anything on China or the border dispute.

India says China occupies 38,000 square kilometres (14,700 square miles) of its Himalayan territory, while Beijing claims all of Arunachal Pradesh, which covers 90,000 square kilometres.

A formal ceasefire line was never drawn after a brief 1962 war, but the militarised border has remained mostly peaceful, especially since 1996, when the two sides signed a pact to maintain "tranquillity" on their frontiers.

Since then, Beijing and New Delhi have held 13 rounds of border resolution talks, most recently in August.

Efforts to resolve the dispute come amid stepped-up political and trade contact between the world's two most populous nations, with China now India's second-largest trading partner.