CHICAGO: The top American law enforcement official Wednesday escalated a war of words with the nation's third largest city Chicago over its resistance to tougher immigration policies.

Attorney General Jeff Sessions's comments were part of efforts to pressure "sanctuary cities" to increase cooperation with immigration enforcement or lose federal funding.

Instead, Chicago last week sued the Trump administration over the funding threats. California, the most populous US state, and the city of San Francisco have also sued.

Speaking in Miami -- where "sanctuary" policies were abandoned to retain federal money -- Sessions suggested local crime dropped because of the increased cooperation.

He pointed to the July 4 Independence Day holiday weekend, during which he said there were no murders in Miami and 15 in Chicago.

"We cannot continue giving taxpayer money to cities that actively undermine the safety and efficacy of federal law enforcement efforts," Sessions said.

"For the sake of the city, Chicago's leaders need to recommit to policies that punish criminals, instead of protecting them."