Joe Biden also called for the release of the secret complaint about the call filed by a whistleblower

Joe Biden on Friday demanded Donald Trump release the transcript of a call in which the US president reportedly pressured his Ukrainian counterpart for political gain, an act the Democratic presidential hopeful denounced as "clear-cut corruption."

Trump "should immediately release the transcript of the call in question, so that the American people can judge for themselves," Biden said, and also instruct the director of national intelligence to "stop stonewalling" and release to Congress the secret complaint about the call filed by a whistleblower.

Trump spoke by phone with Ukraine's new President Volodymyr Zelensky on July 25, a call US media said featured Trump seeking to coerce his counterpart into launching an investigation of Biden's son in order to dig up information that could damage Biden's 2020 presidential bid.

"Such clear-cut corruption damages and diminishes our institutions of government by making them tools of a personal political vendetta," Biden said in a statement.