US President Donald Trump announced on Monday that he would send the US National Guard to Washington to restore security and order in the US capital.

"I will be sending the National Guard to help restore law and order and public safety in Washington, D.C.," Trump told reporters.

Trump confirmed that 800 National Guard members had been called up to the capital, adding that he might call in the military"if necessary," according to the American website Axios.

"The capital has been taken over by violent gangs, bloodthirsty criminals, roving mobs, reckless youth, drug addicts and homeless people, and we will not allow that to happen again," he added.

The statement comes as Trump is calling the capital's"liberation day," which he has described as "one of the most dangerous cities in the world," despite violent crime rates declining in the area for the second year in a row.

The website indicated that Trump could temporarily take over the Washington Metropolitan Police Department under city law.