A US senator has released internal government documents showing the Trump administration transferred millions of dollars from its disaster relief agency to fund increased immigration enforcement.

The documents, released by senator Jeff Merkley of Oregon, show the Department of Homeland Security (DHS) took approximately $9.8m (£7.5m) from the Federal Emergency Management Agency (Fema) to fund more transportation and removal efforts, as well as more detention beds, for suspected undocumented immigrants.

The release of the documents comes after the administration’s much-criticised decision to separate immigrant children from their families when they were caught crossing the border between checkpoints. It also comes as several US states are bracing for what could be one of the worst hurricanes in decades – a crisis that will primarily fall to Fema to tackle.

Mr Merkley called the funding transfer a “scandal” in a statement.

“It wasn’t enough to rip thousands of children out of the arms of their parents – the administration chose to partly pay for this horrific programme by taking away from the ability to respond to damage from this year’s upcoming and potentially devastating hurricane season,” he said.

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The funding for Immigration and Customs Enforcement (ICE) came primarily from Fema’s training, travel, and public engagement budget, according to the documents.

DHS spokesman Tyler Houlton said that no disaster relief funding had been transferred from Fema to ICE, and that the money in question could not have been used for hurricane response “due to appropriation limitations”.

“This is a sorry attempt to push a false agenda at a time when the administration is focused on assisting millions on the East Coast facing a catastrophic disaster,” he wrote on Twitter.

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The documents, obtained by CNN, show the transfer made up less than 1 per cent of Fema’s total $1.03bn budget. Nine other agencies saw similar proportions of their budget taken this year to fund ICE’s need for increased transportation and removal activities and detention beds.

“Without the transfers and reprogramming identified in this notification, ICE will not be able to fulfil its adult detention requirements in FY 2018,” the documents state, adding that insufficient funding could require the agency to release any new detainees.

“ICE will not be able to deport those who have violated immigration laws,” the documents continue. “ICE could also be forced to reduce its current interior enforcement operations, curtailing criminal alien and fugitive arrests, which would pose a significant risk to public safety and national security by permitting known offenders to remain at large.”

The number of ICE arrests increased more than 40 per cent during Mr Trump’s first year in office, according to agency records. The increase was driven largely by a nearly 200 per cent increase in the number of immigrants without a criminal record arrested by the agency.