Trump defends census citizenship question

US President Donald Trump has defended adding a citizenship question to the census after ordering documents that could shed light on the decision should be kept under wraps.

He said it would be "ridiculous" not to ask the question, but critics say it is racially motivated.

Democrats later voted to hold Trump administration officials in contempt for refusing to turn over the files.

A question on citizenship has not appeared on any US census since 1950.

The once-a-decade population count helps the US government draw up districts for state and local elections and guides the distribution of billions of dollars in federal funds.

Asked about the matter at the White House on Wednesday, he told reporters: "When you have a census and you're not allowed to talk about whether or not somebody's a citizen or not, that doesn't sound so good to me.

"It's totally ridiculous that we would have a census without asking."

The Trump administration maintains that rather than being discriminatory, the question is needed to enforce 1965 Voting Rights Act protections for racial minorities.

The Democratic-led House Oversight Committee voted 24-15 to hold Attorney General William Barr and Commerce Secretary Wilbur Ross in contempt for ignoring congressional legal orders demanding the material.