Special Counsel Robert Mueller will not deliver his long-awaited report next week on Russian interference in the 2016 U.S. elections, a senior U.S. Justice Department official said on Friday, amid expectations that the report was imminent.

"Any reports that the Special Counsel's report will be delivered to the DOJ (Department of Justice) during the week of Feb. 28 are incorrect," the official said, speaking on condition of anonymity.

The 21-month Mueller investigation, also focused on possible obstruction of justice, has been a dark cloud over Donald Trump's presidency, with reports of its conclusion being imminent appearing frequently in recent weeks.