President Trump's economic adviser Kevin Hassett issued a harsh criticism of a think tank that published a critical analysis of the Republican tax reform plan — while visiting that same think tank.

Speaking at the Tax Policy Center, Hassett lit into the report the group published Friday that found the Republican tax plan would lose $2.4 trillion in revenues and raise taxes on many middle-income families while giving big tax breaks to high earners.

The analysis, Hassett said, contained "many fictions" and "scientifically indefensible" conclusions.

In recent days, congressional Republicans have criticized the Tax Policy Center, a nonprofit, nonpartisan think tank, as tilted to the left.

Hassett said Thursday the backlash has been justified.

"I think that's what happens when you behave irresponsibly," he declared to a room of people that included the tax experts who wrote the analysis, arguing the think tank did not have critical details about the Republican plan necessary to score its effects.

Hassett, a Ph.D. economist who formerly was a scholar at the conservative American Enterprise Institute, then presented the case that the GOP plan to lower corporate tax rates would benefit workers and increase economic growth, based on economic research.

Countries like France and Greece, he noted, have pursued lower corporate tax rates than the U.S.

And when the United Kingdom lowered its corporate tax rate, he noted, tax revenues surged past forecasts.