"We consider it unacceptable when, under the pretext of protecting the civilian population, terrorists want to be taken out from under attack, as well as inflict damage on Syrian government troops," the Russian president said.
He noted that this seems to be precisely what attempts to "stage the use of poisonous substances by the Syrian authorities".
"We have irrefutable evidence of training militants for such operations, for such provocations," Putin added.
Earlier, Putin called for giving a systematic character to humanitarian efforts in Syria.