President Donald Trump on Wednesday said talks on the Iran crisis would be held behind closed doors and that "only one group of meaningful 'POINTS'" was acceptable to the United States, but gave no other details about the negotiations.

"These are the POINTS that are the basis on which we agreed to a CEASEFIRE. It is something that is reasonable, and can easily be dispensed with," he said in a social media post.

Trump separately told ABC News in an interview that he expects talks to begin on Friday and to move very quickly.

Pakistani Prime Minister Shehbaz Sharif earlier on Wednesday said U.S. and Iranian delegations would be arriving in Pakistan on Friday after the two nations accepted a two-week ceasefire.

Trump in his online post also threatened a federal probe into unnamed individuals he accused — without providing evidence — of circulating various correspondence that he said were not the basis for the ceasefire agreement.