Russian Foreign Minister Sergei Lavrov said on Friday that Iran's accidental shooting down of a Ukrainian airliner on January 8 occurred at a time when Tehran was spooked by reports of advanced U.S. stealth fighters in the area.

"There were at least six (U.S.) F-35 fighters in the air in the Iranian border area (at the time). This information has yet to be verified, but I'd like to underline the edginess that always accompanies such situations," Lavrov said, according to the New York Times.

Lavrov, speaking at his annual news conference in Moscow, called the incident a human error and said he was not trying to excuse anyone for what happened.

But he said it was important to understand the context and that the incident had occurred hours after an Iranian missile attack on U.S. bases in Iraq, when Iranian forces were braced for some kind of U.S. military retaliation.

"There is information that the Iranians were expecting another attack from the United States after the strike but did not know what form it might take," said Lavrov.