US President Donald Trump has threatened to send agents from Immigration and Customs Enforcement (ICE) to provide security at airports, unless a deal is reached to fund the Department of Homeland Security (DHS).

"I will move our brilliant and patriotic ICE Agents to the Airports where they will do Security like no one has ever seen before," Trump posted on Truth Social on Saturday.

The DHS has gone without funding since mid-February, after Congress failed to reach a funding agreement - leaving normal airport security without pay.

A bill that would fund DHS and provide payments for Transportation Security Administration (TSA) agents at airports failed to advance in the Senate on Friday.

The Trump administration has blamed the delay on Democrats, who have declined to pass funding without reforms to ICE, which operates under DHS.