Influential US Senator John McCain, a Vietnam war hero and a towering figure in the American political scene, who turned out to be a prominent critic of President Donald Trump has died following a battle with an aggressive form of brain cancer.

He was 81. McCain, a six-term senator from Arizona, who was a friend of India, had been suffering from a malignant brain tumour, called a glioblastoma, for which he had been treated periodically with radiation and chemotherapy since its discovery in 2017.