Special counsel Robert Mueller and the team he assembled to investigate U.S. President Donald Trump and his associates have been funded through the end of September 2019, three U.S. officials said on Monday, an indication that the probe has funding to keep it going for months if need be.

The operations and funding of Mueller's office were not addressed in the budget requests for the next government fiscal year issued by the White House and Justice Department on Monday because Mueller's office is financed by the U.S. Treasury under special regulations issued by the Justice Department, the officials said.

"The special counsel is funded by the Independent Counsel appropriation, a permanent indefinite appropriation established in the Department's 1988 Appropriations Act," a Justice Department spokesman said.