San Francisco, Nov 20 (IANS): A US federal judge has stopped President Donald Trump's administration from refusing asylum to immigrants who cross the country's southern border illegally.

US District Judge Jon S. Tigar issued a temporary restraining order after hearing arguments on Monday night in San Francisco, NBC News reported.

The request was made by the American Civil Liberties Union (ACLU) and the Centre for Constitutional Rights, which quickly sued the administration after Trump issued the ban earlier this month in response to the caravans of migrants that have started to arrive at the US-Mexico border.

In a proclamation on November 9, Trump said that anyone who crossed the southern border would be ineligible for asylum.

The regulations, which will remain in place for three months absent a court order, could potentially make it harder for thousands of people who enter the US to avoid deportation.

In recent years, tens of thousands of immigrants each year have shown up in the Arizona desert or on the north bank of the Rio Grande in Texas, surrendered to immigration agents and requested asylum, NBC News said.

The Department of Homeland Security estimates around 70,000 people a year claim asylum between official ports of entry.

Trump has argued that the migrant caravans were a threat to national security.

Around 3,000 people from the first of the caravans have arrived in Tijuana, Mexico, across the border from San Diego, California.

US Customs and Border Protection said earlier on Monday that it closed off northbound traffic for several hours at the San Ysidro crossing.

It has also installed movable, wire-topped barriers, apparently to stop a potential mass rush of people.

As of Monday, 107 people detained between official crossings have sought asylum since Trump's order went into effect.