S officials detained nearly 100,000 migrants at the border with Mexico in February, according to two people familiar with preliminary figures, the highest monthly total since mid 2019.

The previously unreported figures show the scope of a migrant influx, which has only grown since US President Joe Biden took office and sought to roll back some of predecessor Donald Trump's restrictive policies.

The nearly 100,000 migrants detained appears to be the highest monthly numbers since June 2019 during a large border surge, which Trump cited as justification for a broad immigration crackdown.

And an increasing number of Children arriving at the border without a parent or legal guardian has forced US officials to scramble for housing options in recent weeks and try speeding up their release to US sponsors.

Republicans have criticized Biden for rolling back Trump's hardline immigration policies, claiming that will lead to more illegal immigration.

One of those Trump era measures is Title 42 which was issued during the global health crisis allowing US authorities to rapidly expel migrants caught crossing the border illegally.

Under that policy, the number of migrants attempting to illegally cross the border again has actually increased over the past year, with some making another attempt.

After being caught, Biden exempted unaccompanied Children from Title 42 in February.