More than 103,000 migrants were arrested or denied at the Mexico border in March, a 35 percent increase over the month before and more than twice as many as the same period last year, according to new data from US Customs and Border Protection.

About 92,000 of the 103,000 migrants were apprehended between ports of entry, while the remaining 11,000 appeared at ports of entry to claim asylum and were deemed 'inadmissible'.

After the new data was released on Tuesday, CBP's Chief of Law Enforcement Operations Brian Hastings told reporters: 'We've arrived at the breaking point.'

'The current situation is unsustainable for border control operations,' he added.

More than 103,000 migrants were arrested or denied at the Mexico border in March, according to data released by US Customs and Border Protection on Tuesday (file photo)

Rio Grande Valley Sector Chief Patrol Agent Rodolfo Karisch spoke at a Senate Homeland Security Committee hearing the same day and said a caravan-size influx of migrants comes through his sector each week.

'Much media attention has focused on caravans coming across from Central America,' Karisch said. 'But the fact is that RGV is receiving caravan-equivalent numbers every seven days.'

The official said his sector has apprehended people from 50 different countries, including China, Bangladesh, Turkey, Egypt and Romania.

Rio Grande Valley Sector Chief Patrol Agent Rodolfo Karisch addressed the Senate Homeland Security Committee on Tuesday and said a caravan-size influx of migrants comes through his sector each week

The steady increase in migrant arrivals, which has been building over the past several months, is driven by a growing number of children and families, especially from Central America.

Children and people traveling as families made up 67 percent of those arrested by Border Patrol agents between official ports of entry last month, officials said. In March 2018, the same category made up one third of arrests.

President Donald Trump has grown increasingly frustrated with the rising number of Central American migrants attempting to cross the southern border, and his ire has been directed at his own officials, Congress, and Latin American countries, who he says have not done enough to stop their citizens from traveling to the United States.

On Sunday, Trump's top homeland security official, Kirstjen Nielsen, said she was stepping down, and a senior administration official said other agency leaders had not done enough to crack down on the surge in immigration.

Immigration experts believe more migrants are likely to attempt to cross in the coming months, as numbers typically peak around May.