US President Donald Trump on Wednesday called for jailing the mayor of Chicago and governor of Illinois in an escalation of his extraordinary attacks on political opponents.

“Chicago Mayor should be in jail for failing to protect Ice Officers! Governor Pritzker also!” Trump posted on social media. “My goal is very simple. STOP CRIME IN AMERICA!”

Neither Chicago Mayor Brandon Johnson nor Illinois Governor JB Pritzker have been accused of criminal wrongdoing.

Trump’s call to imprison the two prominent opponents of his immigration crackdown comes as another high-profile political rival, former FBI Director James Comey, was due to appear in court to face criminal charges that have been widely criticised as flimsy.

Trump’s government has targeted Democratic-run cities around the nation for raids on migrants, often conducted by masked, plain clothes agents.

The crackdown fulfils a key promise made by Trump in his election victory last year, where he described the United States as under attack by waves of foreign “criminals”.