A US federal judge has blocked one of President Donald Trump's first executive orders aimed at tightening the country’s immigration policy.

The executive order, which Trump signed into law on the day of his inauguration, bans asylum seekers from crossing the Mexican-US border.

US District Judge Randolph Moss found that the president overstepped his authority.

Moss, in a 128-page ruling, noted that neither the residency law nor the US Constitution allows the head of state to cancel existing procedures to provide asylum in the US, Bild reports.

The judge added that Trump cannot ignore the laws even in the face of serious challenges to illegal immigration.

The White House has announced that it will appeal this decision.