However, he added that it would not be enough with Kiev's continuing military operation against the rebels, adding that the West must push Ukraine's authorities to declare a ceasefire.
"Russia will do everything in its power for a full, comprehensive, deep, and transparent investigation," Putin told a meeting of the national security council, according to excerpts broadcast by Russian state television.
"We are asked to exert influence on the militants of the south-east (of Ukraine). Of course we will do everything in our power.
"Tanks broke through to the train station," he said of Monday's clashes on the outskirts of Donetsk.
"International experts who came to the tragedy could not lift their heads."
Ukrainian "authorities must be called upon to abide by elementary decency, to introduce a ceasefire, at least for a short time for the investigation," Putin added.