They are simply called "Minister".
Ambassador.
Informal diplomatic message
He was US minister to Russia from 1832-1833.
Spain's Minister de Lome was less then diplomatic.
Adams was a minister to Britain and to the Netherlands. He was also part of a three-man diplomatic team sent to France.
Edmond Genet is the minister who precipitated a major diplomatic crisis by seeking American aid for France. He was the French ambassador to the United States in the late 1700s during the French Revolution.
chancellory
how to spell the prime minister's name
George Yeo is Singapore's Minister for Foreign Affairs. He establishes diplomatic foreign relationships with important politicians of other countries.
the name of the minister of health
The name of Uganda's Minister of Health is Ruhakana Rugunda.
The name of Uganda's Minister of Defence is Crispus Kiyonga.