The group posted on its Twitter page: "WikiLeaks to release CIA paper tomorrow."
The website set off a firestorm recently when it posted some 76,000 U.S. documents related to the war in Afghanistan. The group has said it has another 15,000 documents, which it plans to release soon.
It was not immediately clear whether the Twitter post on Tuesday is related to the batch of documents that WikiLeaks has called the "Afghan War Diary."
The U.S. Defense Department has demanded WikiLeaks return all documents belonging to the Pentagon and delete any records of them. Officials in Afghanistan have also criticized the leak.
Founder and editor of the website, Julian Assange, was arrested in absentia last week in Sweden on charges of rape. The warrant was revoked less than a day later by Chief Prosecutor Eva Finne.
Assange told the Arabic-language television network Al-Jazeera on Sunday the accusations are "clearly a smear campaign."
"The only question is, who was involved?" he asked, declining to say who he thinks is behind the effort.
Separately on Tuesday, the attorney for the alleged victims told CNN rumors that the Pentagon or CIA was somehow involved in the sex crime accusations against Assange are "complete nonsense."