A caravan in Mexico of at least 1,000 migrants resumed its march northward towards the US border on Monday, accusing Mexican authorities of failing to fulfill their promise of granting humanitarian visas.

Carrying a banner that read “Exodus from poverty” and chanting “We are not criminals. We are international workers,” the migrants set off at dawn from the town of Arriaga in the southern state of Chiapas.

The same group of migrants had decided to disband a previous caravan that set off from Chiapas on Christmas Eve, after immigration officials agreed to address demands that included visas that would allow them to travel freely through Mexico.

Authorities “failed to fulfill” the pledge, said Luis Garcia Villagran, an activist accompanying the caravan.

“They left them (the migrants) in shelters… they separated the families and caused serious problems,” he told reporters.

The migrants, who include families with children, many of them from Central America and Venezuela, complained that they had been misled.

“Immigration lied to us. They made a promise that they didn’t keep. They just wanted to break up the group,” said Rosa Vasquez from El Salvador.

A surge in migration was top of the agenda when Secretary of State Antony Blinken and other senior US officials visited Mexico last month seeking increased efforts to curb the flow.

Right-wing US Republicans in Congress have blocked President Joe Biden’s request for additional funding to Ukraine and Israel, demanding he agree to sweeping new measures against illegal migration in exchange.

In the weeks before Blinken’s visit, US border police had reported around 10,000 crossings every day by migrants, many of them fleeing poverty and violence in their home countries.

While some pay people smugglers to transport them in trucks through Mexico, others join caravans undertaking the long journey on foot, enduring hunger, exhaustion and insecurity.