"We remain seriously concerned about the situation in the East China Sea and the South China Sea. We reiterate our strong opposition to any destabilising or unilateral actions including by force or coercion that threaten peace and stability in the region," US Secretary of State Marco Rubio and his three counterparts said in a joint statement after talks in New Delhi.

In clear but unstated references to China, the foreign ministers criticised "dangerous manoeuvres by military aircraft" and "ramming and blocking actions in the South China Sea", and said they were "seriously concerned by the militarisation of disputed features" in the waters where Beijing stakes wide claims.

Separately, the ministers condemned Iran's planned imposition of tolls in the Strait of Hormuz, part of its retaliation for a US-Israeli attack, and called for "uninterrupted flow of global commerce through the Strait of Hormuz and the Red Sea".

"We reiterate the importance of adhering to international law as reflected in the United Nations Convention on the Law of the Sea," the ministers said of the treaty, which the United States has refused to join.