Vietnam expects frank talks over disputed maritime territory in the South China Sea when the leader of the country's communist party travels to Beijing next week, an official said on Thursday.

Communist Party General Secretary Nguyen Phu Trong will visit China from October 11 to 15 at the invitation of President Hu Jintao.

Among the wide range of issues to be discussed are the two country's conflicting sovereignty claims in what Vietnam calls the East Sea, said Vietnamese foreign ministry spokesman Luong Thanh Nghi.

"We think that the existing matters in the bilateral relations, including the marine issues, will be discussed in a frank and sincere manner," Nghi told reporters.

"Settling disputes in the East Sea is a long-term, difficult and complicated process requiring efforts and a practical and objective approach by both sides."

China is Vietnam's largest trading partner but the communist neighbours have a long-standing dispute over sovereignty of the potentially oil-rich Paracel and Spratly island groups, which straddle vital commercial shipping lanes.

Relations sank to their lowest point in years in May and June when Vietnam said Chinese vessels twice interfered with its oil survey ships inside the country's exclusive economic zone.