Republican presidential candidate Donald Trump has denied masquerading as a spokesman for himself in the 1990s after an audio tape was published.

The Washington Post says it obtained a 1991 phone conversation between a PR man calling himself John Miller, but sounding like Mr Trump, and a reporter.

Mr Trump said the voice on the tape did not belong to him.

Reporters who covered his early career say they regularly spoke to a Trump spokesman sounding exactly like him.

They would hear from the "spokesman", named as John Miller or John Baron, when asking to interview Mr Trump.

Mr Trump is the presumptive Republican nominee after pushing out more than a dozen Republican rivals in the race for the White House.

Traditional Republicans are warming to him to unify the party and beat likely Democratic nominee Hillary Clinton.