China's top diplomat scolded Vietnamese officials during talks in Hanoi on Wednesday for "hyping up" a row over a Chinese oil rig drilling in disputed waters in the South China Sea, in tough comments that suggest relations will remain rocky. State Councilor Yang Jiechi also told his hosts that the rig's activities in waters also claimed by Vietnam were "completely legal", China's Foreign Ministry spokeswoman Hua Chunying said at a daily briefing in Beijing. Yang, who outranks the country's foreign minister, made the remarks in a meeting with Vietnamese Deputy Prime Minister and Foreign Minister Pham Binh Minh. Before the visit, experts had said many obstacles remained to resolving one of the worst breakdowns in Sino-Vietnamese relations since the neighbours fought a brief war in 1979.