LONG-SERVING Arizona senator John McCain died at the weekend from a brain tumour, just hours after announcing that he would discontinue medical treatment.

The former naval pilot, who was shot down over the Vietnamese capital Hanoi in 1967 and held as a prisoner of war for more than five years, was routinely eulogised as a war hero by political allies and opponents in the US.

Former president Barack Obama, who defeated Mr McCain in the 2008 election, said that, despite their differences, they shared a “fidelity to something higher — the ideals for which generations of Americans and immigrants alike have fought, marched, and sacrificed.”

George W Bush, who pipped the conservative Arizona senator for the 2000 Republican presidential nomination, called him a "man of deep conviction and a patriot of the highest order" and a "friend whom I'll deeply miss.”

Even Donald Trump, who questioned Mr McCain’s heroic status when they fought each other for the 2016 Republican candidacy, belatedly tweeted: “My deepest sympathies and respect go out to the family of Senator John McCain. Our hearts and prayers are with you!”

He ordered White House flags to be flown at half-mast.

It is believed Mr McCain told his family that he did not want the US president attending his funeral.

Democratic Party presidential hopeful Bernie Sanders, who worked on some issues with Mr McCain in the Senate, called him “an American hero, a man of decency and honour and a friend of mine.

“He will be missed not just in the US Senate but by all Americans who respect integrity and independence.”

German Foreign Minister Heiko Maas issued a point-scoring tribute, saying that Mr McCain “stood for an America that is a reliable and close partner — an America that takes responsibility for others out of strength, stands by its values and principles even in difficult moments and bases its claim to leadership on that.”

Israeli Prime Minister Benjamin Netanyahu saluted someone whose “support for Israel never wavered. It sprang from his belief in democracy and freedom.”

Former Vietnamese ambassador to Washington Nguyen Quoc Cuong praised his postwar role in helping to normalise bilateral relations.