Donald Trump dismissed the remarks saying he's "perfectly prepared" for meetings with Vladmir Putin.

US President Donald Trump was less prepared than Vladimir Putin for their first meeting, allowing his Russian counterpart to promote his own agenda and leaving US officials at a disadvantage, former Secretary of State Rex Tillerson has told lawmakers.

Tillerson, who was fired by Trump last March, delivered his assessment of Trump's approach to the talks in Hamburg in 2017, in remarks to a Congress committee Tuesday reported by the Washington Post.

"We spent a lot of time in the conversation talking about how Putin seized every opportunity to push what he wanted," a committee aide told the newspaper.

"There was a discrepancy in preparation, and it created an unequal footing."

Trump met with Putin on the sidelines of the G20 summit in July 2017 under a cloud of rebuke for his reluctance to criticize the Russian leader directly over Moscow's meddling in US elections the previous year.

He later said he got along with Putin "very, very well" at the meeting.

Tillerson attended the Hamburg talks, which were intended to be a brief meeting but span out into a two-hour discussion on a variety of global issues, anonymous committee aids told the Washington Post.

The following year Trump met again with Putin for their first formal summit in Helsinki, dismissing top aides for two hours of talks, in a sharp break with standard diplomatic practice.

The businessman-turned-politician has previously expressed skepticism about the importance of preparation for high-stakes diplomacy, describing "attitude" as more useful than research.

Ahead of his first meeting with North Korean leader Kim Jong Un in Singapore last year, Trump said with characteristic bravado: "I don't think I have to prepare very much... It's about attitude, it's about willingness to get things done."

Trump dismissed Tillerson's remarks, claiming he was "perfectly prepared" for meetings with Putin.

"We did very well at those meetings," he said, according to the newspaper.

Tillerson has previously described Trump as an "undisciplined" figure who repeatedly wanted to break the law -- leading the US president to respond that his onetime cabinet member was "dumb as a rock" and lazy as hell."