The U.S. Justice Department's internal watchdog said he expects to be able to release on Dec. 9 a long-awaited report on the origins of investigations into alleged Russian interference in the 2016 U.S. presidential election.

In a letter sent on Thursday to Senate Judiciary Committee Chairman Lindsey Graham, Justice Department Inspector General Michael Horowitz said that he expected his office to be able to release the report on Dec. 9 "barring unforeseen circumstances."

Supporters of President Donald Trump have claimed the report will raise questions about the legitimacy of FBI investigations into alleged links to Russia by Trump and some of his campaign advisers.

A central issue the Inspector General's office said the report will examine is how closely the FBI stuck to the law and rules when it went to a secret Foreign Intelligence Surveillance Court beginning in 2016 to obtain authorization to conduct electronic monitoring of "a certain U.S. person."

Carter Page, a one-time foreign policy adviser to Trump's 2016 campaign, recently sued the Justice Department, accusing it of violating his privacy by failing to give him an opportunity to examine the report before publication.

As of Wednesday, Page told Reuters he had not been allowed to examine a draft of the document.

Another individual questioned at length last summer by representatives of the Inspector General's office in connection with the forthcoming report was Christopher Steele, a former British intelligence officer who compiled a controversial "dossier" on alleged links between Trump and Russia for Democratic presidential candidate Hillary Clinton and Democratic Party lawyers.

The FBI cited reporting by Steele in documents sent to the Foreign Intelligence court when it sought permission to monitor Carter Page, though other information used by the FBI in such applications remains classified.