A senior US diplomat has called on China to clarify its territorial claims in the South China Sea in accordance with international law.
Daniel Russel, assistant secretary of state for East Asia, criticised China's so-called 'nine-dash line' that outlines its claims.
He added that there were growing concerns over Beijing's pattern of behaviour.
China, the Philippines, Brunei, Malaysia, Vietnam and Taiwan all have claims in the region.
Russel told a congressional committee that there are growing concerns that this pattern of behaviour in the South China Sea reflects incremental effort by China to assert control over the area, despite objections of its neighbours
He added that any Chinese claim to maritime rights not based on claimed land features would be inconsistent with international law, the report added.