Washington, July 27 (TIWN) A Republican Senator for the US state of Arkansas has described slavery as a "necessary evil" on which the American nation was built, the media reported on Monday.

Republican Senator Tom Cotton said US founders viewed slavery as a "necessary evil upon which the union was built".

His comments were criticised as an attempt justify the slavery of black people.

He is introducing legislation to ban federal funds for a project by the New York Times newspaper, aimed at revising the historical view of slavery.

The project's founder expressed outrage at the remarks.