US President Donald Trump expelled all ambassadors to foreign countries and international organizations on his first day in office, according to reports.

Axar.az reports that, Trump, who was sworn into office as the 45th president of the United States on Friday, had demanded that all ambassadors appointed by his predecessor Barack Obama leave their offices on the same day with no grace period.

As many as 80 ambassadors for countries, agencies and issues, including the ambassador for global women's issues, have been discarded.

According to common policy, politically-appointed ambassadors resign at the start of a new administration, but it is less common to have no replacements in line.

Trump's transition team had announced the decision to foreign ambassadors on December 23.

The move risks cutting all direct connections of the US with Germany, the UK and Canada, as well as other critical allies.

In addition, countries such as China, India, Japan and Saudi Arabia will be waiting for replacements, a lengthy process that is carried out by the US Congress.

So far, few appointments have been made, including South Carolina governor Nikki Hayley, who replaced Samantha Power as the US ambassador to the United Nations.

Also, bankruptcy lawyer David Friedman and Iowa Governor Terry Branstad have been appointed ambassadors to Israel and China respectively.

Trump has been under criticism for other major staffing gaps below cabinet level.