By Asif Shahzad

ISLAMABAD (Reuters) -Pakistan will open criminal proceedings against former prime minister Imran Khan on charges of exposing official secrets, Interior Minister Rana Sanaullah said on Wednesday, the latest in a string of cases the former premier has been facing.

The case is related to diplomatic correspondence between Washington and Islamabad, which Khan said early last year was part of a U.S. conspiracy to topple his government. Washington has denied being involved in any such conspiracy.

The decision was taken after Khan's former principal secretary Azam Khan recorded a court statement on Wednesday to the effect that a U.S. diplomatic encrypted letter was manipulated by Khan in March 2022 to serve his political goals, Sanaullah said.

The 70-year-old former cricket hero lost power in a vote of no confidence in April 2022, in which he has said Washington got involved after his visit to Moscow.

Khan waved a piece of paper in a public gathering shortly after his removal saying he was holding a copy of a secret diplomatic letter, which spoke of dire consequences if he continued getting closer to Russia.

Khan travelled to Moscow on the eve of Russia's invasion of Ukraine.

Sanaullah said the principal secretary also testified that Khan told him he had lost the copy of the letter when he was asked for its return.

"It is a crime to expose an official secret," the interior minister said, adding the state will be filing the charges in the court against Khan.

"I don't think he lost the copy. He still has it. It has to be recovered from him," he said.

Khan said he did not believe his former secretary could testify against him. "I will not accept it as long as I don't hear it from him directly," he told reporters after a court hearing in another case.

In a tweet on Wednesday evening, Khan said, "In their feverish attempts to implicate me in any case just to get me disqualified and jailed, this current assortment of incompetent crooks have again shot themselves in the foot. They have provided me with an opportunity to do a proper exposé of this whole Cypher drama."

"Tomorrow I will share the uncensored details of how this conspiracy unfolded to overthrow a govt which had the best economic performance in the last 17 years and bring these money launderers and crooks into power who have run the country to the ground," Khan added.

The secrecy charge is the latest in a multitude of charges Khan has faced since his ouster, including graft, murder and sedition.

(Reporting by Asif Shahzad; Editing by Andrew Heavens, Tomasz Janowski, Alexandra Hudson)