President Donald Trump has warned Honduras, Guatemala and El Salvador against allowing people who intend to travel into the US illegally to pass through their borders.

He tweeted on Tuesday night: ‘We have today informed the countries of Honduras, Guatemala and El Salvador that if they allow their citizens, or others, to journey through their borders and up to the United States, with the intention of entering our country illegally, all payments made to them will STOP (END)!’

He then added: ‘Anybody entering the United States illegally will be arrested and detained, prior to being sent back to their country!’

Earlier in the day, Trump tweeted to say he had warned Honduras he will cut millions of dollars in aid if a group of about 2,000 migrants is allowed to reach the United States.

A migrant caravan set out on Saturday from the impoverished, violence-plagued country and was headed north on the long journey through Guatemala and Mexico to the U.S. border.

Trump, who has made cracking down on illegal immigration a keystone of his presidency, tweeted that US aid to Honduras, which is planned to reach nearly $66million in 2019, would end.

‘The United States has strongly informed the President of Honduras that if the large Caravan of people heading to the U.S. is not stopped and brought back to Honduras, no more money or aid will be given to Honduras, effective immediately!’ he said.

Guatemala announced it would stop the group from entering if they did not have the proper visas.

However, the migrants – including children – managed to reach a shelter in the southwestern Guatemalan city of Esquipulas on Monday, according to local media reports.  

Rights organizations called on the Guatemalan government to guarantee the migrants safe passage.

‘The government of Guatemala is responsible for the security and integrity of the people who are on its territory and their human rights should not be violated for any reason,’ a statement by 18 migrant support groups said.

‘We demand the cessation of all police and administrative action that restricts their fundamental rights,’ the groups added.

Mexico has also said it would block members of the caravan from entering its territory if they did not have permits.

According to the United Nations, 500,000 people a year cross illegally over Mexico’s southern border in the hope of making it to the U.S.

Most of them are fleeing violence and poverty in Central American countries.

Honduras is a country of nine million people but around one million Hondurans live in the United States, most illegally.

Last year they injected $4billion into the Honduran economy through remittances sent home, amounting to some 20 per cent of gross domestic product.

Last week, Vice President Mike Pence met with the presidents of Honduras, Guatemala and El Salvador in Washington for the second conference on Prosperity and Security in Central America.

Pence asked the three presidents to send a message to their citizens that ‘if they can’t come to the United States legally, they shouldn’t come at all.’

He also acknowledged that greater prosperity in those three countries – known as the Northern Triangle – was vital to encouraging undocumented migrants from making the treacherous path north.

Washington has committed to providing funding for programs that improve security and create development opportunities in a bid to put the brakes on migration.