US Senator Tom Cotton defends slavery remarks

A senator for the state of Arkansas is defending comments he made on slavery in the United States.

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.