WASHINGTON: Democrats in the US House of Representatives, who will control key committees next year, are preparing investigations into what they say was President Donald Trump's politicisation and gutting of US spy agencies, including whether analysts have censored themselves to avoid retaliation.

"There's absolutely evidence that analysts are hesitant to write on topics that they think might be controversial.

"There's absolutely evidence of a decline in morale in the analytic community because of the pressures that they are under," US Representative Jim Himes, a Connecticut Democrat who will become chairman of the House intelligence committee in January, told Reuters on Tuesday.

There has been little scrutiny of the state of the US intelligence community by the Republican-run Congress during the first two years of Trump's second term, during which the administration fired or forced out hundreds of officers and disrupted the production of analyses on key issues, including Iran.