Washington DC - A Pakistani man with alleged ties to Iran has been charged over a supposed scheme to assassinate a politician or government official on US soil, the Department of Justice department claimed on Tuesday.

The DOJ and FBI allege Asif Merchant travelled to the US in April after spending time in Iran.

Once in the US, he contacted a person he believed could assist him with the scheme, but that person reported him to law enforcement, the department alleges.

In mid-June, Merchant met with the purported hitmen, who were in fact undercover law enforcement officers. He was arrested in July.

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"The complaint unsealed today underscores, yet again, that those who engage in lethal plotting on US soil will face the full force of the American justice system," said Assistant Attorney General Matthew Olsen of the department's National Security Division.

"The targeting of former and current officials by foreign actors is an affront to our sovereignty and our democratic institutions and the Department of Justice will use every possible tool to expose and disrupt this egregious activity."

Court documents did not name the alleged targets of the plot.

White House press secretary Karine Jean-Pierre said there was no evidence to suggest the case was connected to the assassination attempt against Donald Trump.

In July, a bullet, or a fragment of one, grazed Trump's right ear and left his face streaked with blood as he was hauled off the stage by Secret Service agents during a campaign rally.