John McCain, the US senator and former Republican presidential nominee, has decided to discontinue treatment for brain cancer.

It was a signal that the war hero had lost his battle and, after a long illness, people close to him said his death was imminent.

In a statement his family said: “Last summer, Senator John McCain shared with Americans the news our family already knew: He had been diagnosed with an aggressive glioblastoma, and the prognosis was serious.

"In the year since, John has surpassed expectations for his survival. But the progress of disease and the inexorable advance of age render their verdict. With his usual strength of will, he has now chosen to discontinue medical treatment.”

Mr McCain was surrounded by his family in Arizona.

In 2008 he was the Republican presidential nominee, losing to Barack Obama.

Mr McCain left Washington at the end of last year but had remained a prominent critic of Donald Trump, particularly over his approach to Russia.

His daughter Meghan McCain said: "My family is deeply appreciative of all the love and generosity you have shown us during this past year.

"Thank you for all your continued support and prayers. We could not have made it this far without you – you’ve given us strength to carry on."

Mr McCain has represented the state of Arizona in Congress for 35 years.

His cancer was discovered in July 2017 and he has not been at the US Capitol in Washington this year. 

He developed a reputation for speaking his mind, which led to a running feud with Mr Trump.

The feud escalated in 2015 when Mr McCain said that Mr Trump’s candidacy had "fired up the crazies".

Mr Trump retorted that the senator was "not a war hero" and added: "I like people who weren’t captured."

Mr McCain’s spent five-and-a-half yeas as a prisoner of war in Vietnam.