WASHINGTON (REUTERS) - US President Donald Trump on Monday (Sept 30) escalated his attacks against the lawmaker leading the impeachment inquiry against him, suggesting that Representative Adam Schiff be arrested for "treason".

The comment is likely to inflame criticism of Mr Trump's handling of the scandal engulfing his presidency, stemming from a telephone call in which Mr Trump asked Ukraine's President Volodymyr Zelenskiy to investigate Democratic rival Joe Biden and his son.

The telephone call was included in an intelligence officer's whistle-blower complaint that raised concerns about whether the President sought to leverage US aid to Ukraine for a political favour.

"Rep. Adam Schiff illegally made up a FAKE & terrible statement, pretended it to be mine as the most important part of my call to the Ukrainian President, and read it aloud to Congress and the American people. It bore NO relationship to what I said on the call. Arrest for Treason?" Mr Trump wrote in a post on Twitter.

Mr Trump appeared to reference statements made by Mr Schiff during a hearing held by the House Intelligence Committee, of which Mr Schiff is the chairman.

Mr Schiff said his remarks parodied Mr Trump's comments on the call with Mr Zelenskiy.

The Republican President has increasingly lashed out at political opponents since House Democrats announced on Tuesday they would pursue an impeachment inquiry.

He likened the whistle-blower and White House officials who gave information to the whistle-blower to spies and suggested they committed treason.

The inspector-general for the director of national intelligence deemed the whistle-blower complaint credible and urgent, while the top US intelligence officer said the whistleblower acted in good faith.