Xinhua file photos of Russian Foreign Minister Sergei Lavrov and Iranian Foreign Minister Mohammad Javad Zarif

The ministers emphasized that U.S. actions are a gross violation of fundamental international law and do not contribute to finding solutions to the complex problems that have accumulated in the Middle East.

MOSCOW, Jan. 4 (Xinhua) -- Russian Foreign Minister Sergei Lavrov and his Iranian counterpart Mohammad Javad Zarif said Saturday that the killing of Iranian Major General Qassem Soleimani violates fundamental international law.

During a phone conversation at the initiative of the Iranian side, Lavrov expressed his condolences over the killing of Soleimani in a U.S. airstrike, the Russian Foreign Ministry said in a statement.

"The ministers emphasized that U.S. actions are a gross violation of fundamental international law and do not contribute to finding solutions to the complex problems that have accumulated in the Middle East, but lead to a new round of escalation of tension in the region," the statement said.

Soleimani, commander of Iran's Islamic Revolution Guards Corps Quds Force, was killed in the U.S. airstrike near Baghdad International Airport.

Iran's top leader Ayatollah Ali Khamenei has vowed "tough revenge" for the deadly attack. ■