A US judge has said he could hold the Trump administration in contempt of court for “willful disregard” of an order to halt the departure of deportation flights carrying more than 200 people to El Salvador last month.

The administration had invoked a 227-year-old law meant to protect the US during wartime to carry out the mass deportation.

“The Court does not reach such conclusion lightly or hastily; indeed, it has given Defendants ample opportunity to rectify or explain their actions. None of their responses has been satisfactory,” federal judge James Boasberg wrote.

The decision to begin contempt proceedings escalates a clash between the White House and the judiciary over the president’s powers.

The administration could avoid a contempt finding, or “purge” itself of contempt, if they provide an explanation of their actions and come into compliance with the original order issued last month, Boasberg said on Wednesday.

That filing is due by 23 April, he said.

Thursday’s decision comes despite the Supreme Court’s later finding that Donald Trump could in fact use the 1798 Alien Enemies Act to conduct the deportations to El Salvador.

The Supreme Court’s ruling against Boasberg’s temporary restraining order “does not excuse the Government’s violation”, he said.

If the administration does not provide the requested information by the 23 April deadline, Boasberg will then seek to identify the individual people who ignored the order to stop the deportations.

He could then recommend prosecutions for those involved.