US President Donald Trump threatens to shut down government over border wall

US President Donald Trump speaks during a rally at Total Sports Park in Washington, Michigan, on April 28, 2018. (Photo by AFP)

US President Donald Trump says he will shut down the federal government in September unless Congress provides more funding for a wall he has promised to build on the border with Mexico.

"That wall has started, we have 1.6 billion (dollars)," Trump said on Saturday at a campaign rally in Washington, Michigan.

"We come up again on September 28th and if we don't get border security we will have no choice, we will close down the country because we need border security."

Trump's proposal for the construction of a 2,000-mile wall has been met with strong criticism both at home and abroad.

The construction work began on April 9, with US Customs and Border Protection officials gathering to mark the groundbreaking of the $73-million project at Santa Teresa near New Mexico’s state line with Texas.

In March, Trump made a similar threat to push for changes in immigration law to help prevent criminals from entering the US.

A $1.3 trillion spending bill, which Trump signed last month to keep the government funded through the end of September, authorized only $1.6 billion for fencing, surveillance technology and other measures related to the wall, although the president originally wanted as much as $25 billion for the project.

The government briefly shut down in January over immigration, but another shutdown ahead of the November mid-elections, on the other hand, is unlikely to be supported by his fellow Republicans who are anxious to keep their control of Congress.

Trump, who had pledged to crack down on immigrants to the US, cited the hundreds of Central American migrants traveling in a "caravan" as one of the reasons he has called for stronger border security.

"Watch the caravan, watch how sad and terrible it is, including for those people and the crime that they inflict on themselves and that others inflict on them," he said on Saturday.

"It's a horrible dangerous journey for them and they come up because they know once they can get here they can walk right into our country."

Immigrants, who include women and children, say they had to flee their homes in Guatemala, El Salvador and Honduras due to death threats from gangs, the murder of family members or political persecution.