U.S. President Donald Trump has asked the over 7,000 Central-American refugees now on the march through Mexico towards the southern border of the United States to “go back”.

He vowed that he would not allow them into the country.

Trump, in a tweet urged them to rather apply for U.S. citizenship like others.

The president had reportedly deployed 800 army troops to the U.S.-Mexico border to stop the migrants.

“To those in the Caravan, turnaround, we are not letting people into the United States illegally.

“Go back to your Country and if you want, apply for citizenship like millions of others are doing!” Trump tweeted.

Trump last week threatened to cut off foreign aid to Honduras, Guatemala and El Salvador should the caravan of people fleeing their homeland attempt to cross into the U.S. illegally.

He alleged that “criminals and unknown Middle Easterners are mixed in”, adding “I have alerted Border Patrol and Military that this is a National Emergency”.

The president also dismissed reports that Russians and Chinese listened to his phone calls for insisting on using his insecure private phone and refusing the secured official lines.

He tweeted: “The New York Times has a new Fake Story that now the Russians and Chinese (glad they finally added China) are listening to all of my calls on cellphones.

“Except that I rarely use a cellphone, and when I do, it’s government authorised.

“I like Hard Lines. Just more made up Fake News!”