US President-elect Donald Trump had harsh words for radical Islamism as he condemned the murder of the Russian ambassador to Turkey and the truck attack on a crowded Christmas market in Berlin.

"Today we offer our condolences to the family and loved ones of Russian Ambassador to Turkey Andrey Karlov, who was assassinated by a radical Islamic terrorist. The murder of an ambassador is a violation of all rules of civilized order and must be universally condemned," Trump said in statement, following the Ankara shooting.

His comments came following the first murder of a Russian ambassador in nearly a century. Ambassador Andrey Karlov was shot as he was speaking at the opening of an exhibition called 'Russia in the Eyes of Turks' at an art gallery in Ankara, Turkey's capital. The gunman has been identified as Mevlut Altintas, a member of Ankara's riot police force.

World leaders and diplomats have been expressing their condolences and outrage over the murder.

In an apparently unrelated incident on Monday, the same day, a truck plowed through a crowd at a Berlin Christmas market, killing 12 people and injuring nearly 50. Authorities now presume it to be an act of terrorism.