President Trump has confirmed he will use emergency powers to build a wall on the US border with Mexico, saying "walls work".

Building the wall was a key pledge of Mr Trump's campaign, but Democrats have described the emergency as a "gross abuse of power".

He is due to sign the plan along with a spending bill aimed at preventing a repeat of a recent government shutdown.

He announced the plan after Congress refused to pay for a wall in the bill.

The declaration will give Mr Trump access to billions of dollars for his project.

"We're going to confront the national security crisis on our southern border," Mr Trump said, as he made the announcement to journalists.

"It's very simple… We want to stop criminals and gangs coming into our country.

"Everyone knows that walls work."