Srilanka, April 18 -- A US senator has met with a man who Trump administration officials have acknowledged was deported in error from Maryland to a mega-prison in El Salvador.

Maryland Senator Chris Van Hollen posted photos of his meeting with Kilmar Abrego Garcia, whom the administration has refused to return to the US despite an order from a federal judge.

After the meeting, El Salvador's President Nayib Bukele also refused to release Mr Abrego Garcia and said he would remain in the country's custody.

The White House has accused Mr Abrego Garcia of being a member of the transnational Salvadoran gang MS-13, a designated foreign terrorist organisation, which his lawyer denies.

It comes amid an escalating showdown between the president...