The United States is preparing plans to suspend immigration and customs processing at airports located in so-called “sanctuary cities”

US Homeland Security Secretary Markwayne Mullin said the Trump administration is preparing plans to suspend customs and immigration processing for international travellers and cargo at major airports in so-called “sanctuary cities” that refuse to cooperate with the administration’s immigration crackdown.

The move could effectively disrupt international air travel and trade at key airports in Democratic-led states, just as millions of foreign visitors are expected to arrive for next month’s FIFA World Cup.

In an interview aired Tuesday on Fox News Channel with Sean Hannity, Mullin said he had discussed the issue with White House officials, though no final decision had been made.

“We are currently — though not initiating it yet — drawing up plans,” Mullin said.

“We shouldn’t be processing international flights into their cities,” he added, referring to sanctuary cities, where he claimed that “local radical left Democrats aren’t allowing us to do our job and enforce federal laws.”

Last week, Reuters and other media outlets reported that Mullin had privately informed US travel industry executives that his department could stop customs and immigration processing for international travellers.

The US Justice Department recently released a list of so-called sanctuary cities and states, including several major cities with international airports such as Boston, Denver, Philadelphia, Chicago, Los Angeles, New York City, Newark, Seattle and San Francisco.

Mullin first raised the possibility publicly in April during a dispute over funding for his department, but on Tuesday indicated the proposal remains under active consideration.

Democrats argue that reforms are needed to curb alleged abuses by Immigration and Customs Enforcement (ICE) and Customs and Border Protection (CBP), including the fatal shooting of two US citizens in Minneapolis in January.

The US Travel Association, representing airlines, hotels, car rental companies and other travel-related businesses, confirmed to Reuters on Friday that its representatives had met with Mullin.

In a statement, the group said Mullin “confirmed his previous comments that the administration is considering a withdrawal of CBP officers from international airports in certain sanctuary cities.”

The association also warned that such a move could have severe consequences for the travel industry and local economies dependent on international tourism.

More than 50 million international travellers passed through New York’s three major airports alone last year.

Airlines for America, which represents major passenger and cargo carriers, also warned last week that reducing customs staffing at major airports would significantly disrupt airline operations, passenger travel and the flow of international cargo.