U.S. President-elect Donald Trump's transition team has issued a blanket mandate requiring politically appointed ambassadors appointed by President Barack Obama to leave their overseas posts by Inauguration Day, The New York Times reported, citing several U.S. diplomats familiar with the plan.

The mandate issued "without exceptions", according to a State Department cable sent on December 23, threatens to leave the United States without Senate-confirmed envoys for months in critical nations like Germany, Canada and Britain, the NYT reported.

In the past, administrations of both parties have often granted extensions to allow a few ambassadors, particularly those with school-age children, to remain in place for weeks or months, the newspaper said.

A senior Trump transition official told NYT there was no illwill in the move, describing it as a simple matter of ensuring Obama's overseas envoys leave the government on schedule, just as thousands of political aides at the White House and in federal agencies must do.

Trump has taken a strict stance against leaving any of Obama's political appointees in place as he prepares to take office on January 20, aiming to break up many of his predecessor's signature foreign and domestic policy achievements, the newspaper said.

Diplomats told NYT the order has thrown their personal lives into a tailspin, leaving them scrambling to secure living arrangements and acquire visas allowing them to stay in their countries so their children can remain in school.

Trump's transition staff was not immediately available for comment.