WASHINGTON: The United States responds to "obviously unfounded" cases and Pakistan Tehreek-e-Insaf (PTI) Chairman Imran Khan's arrest in the Toshakhana case is not one of them, the State Department said Monday.

The comment came during US State Department spokesperson Matthew Miller's press briefing in Washington, where he was asked a slew of questions regarding the PTI chief's arrest.

"We believe that is an internal matter for Pakistan, and we continue to call for the respect of democratic principles, human rights, and rule of law in Pakistan, as we do around the world," he said in response to a question.

The spokesperson had also earlier maintained that the US believes the case of Khan — who was arrested last Saturday, sentenced to three years in prison, and disqualified for five years from running for office — was an internal matter of Pakistan.

A journalist then pressed the State Department's spokesperson further. He said that some people described the response as pretty subdued and muted and wondered whether it was due to Khan's criticism of the US.

In response to this, Miller said: "I think our response to this arrest and his previous arrests have been consistent at all times in declaring it an internal matter for Pakistan."

The journalist then asked how was Khan's arrest different from the case of Russian opposition leader Alexei Navalny — who has been jailed for around two decades in a criminal case. The US called it an "unjust trial".

Miller responded: "So we believe at times there are cases that are so obviously unfounded that is that the United States believes it should say something about the matter. We have not made that determination here."

The journalist then informed Miller that the US had responded to Navalny's arrest. At this, the spokesperson said that they respond when Russia is clearly violating his human rights.

He then asked the spokesperson about Julian Assange, an Australian journalist who leaked official US documents in 2010 and is now behind bars in London as Washington seeks to extradite him.

"Is it, not Britain's (or Australia's) internal matter?" the journalist asked, to which Miller responded: "He has clearly been charged by the US Justice Department."