LIVE: Migrant crisis surges as hundreds of migrants camp at US-Mexico border.

Migrants walk through the river to cross the border between Ciudad Acuña, Mexico and Del Río Texas.

US border agents began expelling plane-loads of mostly Haitian migrants from a large makeshift camp they had set up after wading across the Rio Grande separating Mexico and the United States, with repatriation flights arriving in Haiti on Sunday.

The sprawling camp under the international bridge attracted more than 12,000 migrants at one point and marked a new challenge for U.S. authorities, who have sought to reduce the flow of Central Americans and now hundreds of Haitians who have fled rampant poverty, gang violence and seemingly non-stop natural disasters back home.

U.S. authorities have moved 3,300 migrants since Friday from Del Rio, Texas, and announced a new daily schedule of flights to the Haitian capital, Port-au-Prince, where some officials expressed concern on Sunday for a potentially large influx of returning migrants in the next few days.

U.S. Border Patrol Chief Raul Ortiz told a news conference in Del Rio, Texas, that over the next week the government aims to "quickly" process 12,662 migrants from underneath the bridge that links Del Rio with Ciudad Acuña, Mexico.

"There's no safety in Haiti and there's no work," said Rolin Petit Homme, a 35-year old Haitian who had camped out under the bridge, but says he'll now try to eke out a living in Mexico rather than go back home.

Later on Sunday, the first three flights arrived in Haiti carrying 327 returned migrants, according to a U.S. official. Upon arrival, some said they were never told where they were being taken. read more

Migrants were continuing to cross the river over the weekend despite heightened security on the U.S. side that included horse-mounted agents, one of whom charged his horse to block migrants and swung what looked like a lariat at a person trying to climb up the U.S. embankment from the water. read more

At least 100 Haitians, including families with small children, crossed back into Mexico from under the bridge on Sunday evening, gripping a yellow rope stretched across the river that had risen to chest level.

Many carried backpacks and plastic bags of belongings, and several people told Reuters they planned to stay in Mexico for now because they did not want to be returned to Haiti.

The Sun newspaper brings you the latest breaking news videos and explainers from the UK and around the world

Become a Sun Subscriber and hit the bell to be the first to know

Read The Sun: www.thesun.co.uk

Like The Sun on Facebook: www.facebook.com/thesun/

Follow The Sun on Twitter: twitter.com/TheSun

Subscribe to The Sun on Snapchat: www.snapchat.com/discover/The_Sun/1633225139