Image copyright Getty Images Image caption Hundreds of migrants have made their way to the southern border of Mexico
US President Donald Trump has appealed to Americans to “Stop this big, powerful, illegal invasion” by describing a migrant caravan of some 4,000 people as an “assault on our country”.
The estimated 4,000 people have crossed from Guatemala into Mexico. They are attempting to get to the US border.
The president says they are dangerous “Middle Easterners” and have “joined the caravan”.
Mexico’s President Enrique Pena Nieto has asked the US for protection from “invasive groups” as the migrants come closer to the border.
Mr Trump said on Twitter the illegal immigrants should “go back to their country and if not allowed to come back, leave”.
Image copyright EPA Image caption A man holding his son cries as he waits in the Mexico border city of Tapachula
Image copyright Getty Images Image caption Asylum seekers squeeze into a migrant bus as it leaves from a shelter in the Mexican city of Tapachula
Mr Trump, whose 2016 election victory fuelled calls to block Central American migrants in the US, said: “Many Gang Members and some very bad people are mixed into the Caravan heading to our Southern Border. Please go back, you will not be admitted into the United States unless you go through the legal process. This is an invasion of our Country and our Military is waiting for you!”
In a later tweet, Mr Trump said the migrants wanted to “break into our country” and called on Mr Pena Nieto to halt their advance.
Mexico’s President said he had been in contact with his counterpart Trump and the foreign minister and warned them that “organized criminals” and “infiltrators” were posing a threat.
The United Nations human rights office on Tuesday questioned whether any human rights violations had occurred as the migrants travelled.
Trump: The caravan is an ‘assault on our country’
Image copyright Getty Images Image caption Thousands of people have streamed into Mexico in search of asylum
Image copyright Getty Images Image caption Children play as families wait to cross into Mexico from Guatemala
“The UN human rights office has written to the Mexican government asking to clarify the situation with respect to any alleged rights violations,” a statement said.
“All undocumented asylum seekers deserve to be treated fairly, and any extra-judicial acts or unlawful, unlawful detentions and deportations must be remedied immediately.”
However, the Mexico city of Tapachula said on Wednesday that there were not more migrants waiting at the city’s border crossing than normal.
It is believed most of those heading north do not plan to get to the US border.
Image copyright Getty Images Image caption The migrant caravan originated in Honduras
Image copyright Reuters Image caption Hundreds of migrants have made their way to the southern border of Mexico
The migrant crisis has seen Mr Trump rally support behind his fierce anti-immigration stance.
The wall that Mr Trump has vowed to build along the US border with Mexico is nearly finished, two months after he announced plans to start construction.
Build the Wall Mexico! Build the Wall – Make America Great Again! — Donald J. Trump (@realDonaldTrump) September 8, 2018
On the issue of illegal immigrants, in 2016 Mr Trump won 2 million more votes than Democratic nominee Hillary Clinton, who has been critical of his immigration views.
Image copyright Rex Shutterstock Image caption Mr Trump has repeatedly attacked the 14th amendment which guarantees citizenship to anyone born in the US
Appeals to migrant families’ sense of duty
Image copyright Reuters Image caption Dozens of people have arrived with their children in the city of Tapachula. Many are arriving with a determination to flee their country
Image copyright AFP Image caption The mostly Honduran migrants are seeking asylum in the US, says Fr. Javier Vergara
Mr Trump has accused Mexico of harbouring “bad hombres” because Mexico sent thousands of its citizens who were in the US illegally.
The accusations by Mr Trump has caused concern among the thousands of migrants who have passed through Mexico.
They claim they leave their country because they are worried about gang violence, corruption and murder.