The Russian leader said the depraved terrorists had expanded its control in territory controlled by US and US-backed forces.
ISIS issued Russia with an ultimatum and vowed to execute ten people every day.
Speaking in the Black Sea resort city of Sochi, Putin said the hostages included several US and European nationals.
Putin told the Valdai discussion forum in Sochi: “They have issued ultimatums, specific demands and warned that if these ultimatums are not met they will execute 10 people every day.
“The day before yesterday they executed 10 people.”
Putin did not specify what the militants’ demands were.
He said ISIS detained several nationals south of the Euphrates river in war-torn Syria.
Russia has been engaged militarily in Syria since September 2015, but has aligned itself with Bashar al-Assad’s regime in opposition to Western nations.
Almost 3,000 Russian troops are currently based in Syria.
ISIS militants had taken about 700 hostages in Syria’s Deir-al Zor province after attacking a refugee camp in an area controlled by US-backed forces, according to the TASS news agency.
Officials said militants had kidnapped around 130 families and taken them to the city of Hajin.
It comes just days after Syria declared the delivery of new, modern missiles from Russia as a new means to not only secure Syria but the entire Middle East as Assad aims to increase his regional allies.
Syrian Foreign Minister Walid al-Muallem and Iraqi Foreign Minister Ibrahim al-Jaafari spoke together and praised their countries’ victories over ISIS.
Mr al-Muallem said that the defeat of ISIS “will benefit all the countries of the region and the world”.
Over the past seven years, Syria has faced battles with not only ISIS but airstrikes from Israeli fighter jets as well.
Russia had hoped to maintain a balance between Syria and Israel, but, earlier this year, a Russian II-20 surveillance plane was shot down by Syrian anti-air defence during a response to an Israeli air raid.
Following the incident, Moscow decided to send Damascus multiple S-300 surface-to-air missile systems as a way of enhancing their ally’s defences.
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