The Kremlin on Tuesday issued a rare rebuke to German Chancellor Angela Merkel a day after she criticized Russian air strikes in Syria.

The Kremlin on Tuesday issued a rare rebuke to German Chancellor Angela Merkel a day after she criticized Russian air strikes in Syria.

In Ankara on Monday, Merkel -- referring to air strikes including those carried out by Russia -- said "we are horrified in the face of this human suffering."

Her comments represented some of the sharpest criticism yet of Russia's aerial campaign by Merkel.

Russian President Vladimir Putin's spokesman said Merkel should carefully watch what she said on the Syrian crisis.

"We once again call on everyone to be very careful and responsible in their choice of words, given the already delicate situation in Syria now and the Syrian settlement," Kremlin spokesman Dmitry Peskov said.

Despite complaints from the West and the Syrian opposition, Russia had not received any credible evidence of civilian deaths from air strikes, Peskov said.

He also said no voices had been raised in protest against the "barbaric actions of terrorists" when they assaulted Syrian army forces in the past.

"No one made any statements of this kind at the time," Peskov told reporters.

Syria peace talks were suspended in Switzerland last week.

Asked on Monday whether Russia would press ahead with its bombing campaign in Syria if the peace talks resume, Peskov declined to comment.