"Russian planes in Syria over the past day carried out 46 sorties against 83 infrastructure targets of terrorist groups in the provinces of Hama, Idlib, Damascus, Aleppo and Deir Ezzor," the defense ministry said in a statement.
The one-day tally of targets hit is one of the highest since Moscow began its air campaign in Syria on September 30 to support Assad's forces.
Russia's military said that it destroyed a bomb-making factory belonging to Al-Qaeda affiliate Al-Nusra in the area around the second city of Aleppo, where government forces have renewed a ground offensive.
Russia said it also hit a major Al-Nusra field camp in the Hama region and an ISIL command post in Idlib province.
Russia insists it is targeting ISIL and other groups but the U.S. and its allies are angry at Moscow for hitting other terrorist factions which they call moderate.
The uptick in strikes came as Syrian leader Assad made an unannounced visit to Moscow to meet Putin on Tuesday, his first known foreign trip since the conflict broke out in his country in 2011.
Assad thanked Putin for launching airstrikes in Syria, with both leaders also agreeing during the talks late Tuesday that military operations must be followed by political steps.
As part of a flurry of diplomacy, Russia announced afterwards that Foreign Minister Sergei Lavrov would meet Friday with U.S. Secretary of State John Kerry and their Turkish and Saudi counterparts to discuss Syria.
Putin and Assad's talks focused mainly on military developments, with the Russian leader pledging ongoing support but also urging a political solution to end the war, the Kremlin said.
Assad, who last visited Russia in 2008, told Putin that the three-week-old Russian air war had helped to stop the spread of "terrorism" in his country, the Kremlin said.
Putin's spokesman Dmitry Peskov said Assad's "working visit" was at the invitation of the Kremlin. The Syrian presidency said Wednesday that Assad had returned to Damascus.
Peskov declined to say whether the "lengthy" talks, which included a one-on-one between the leaders and a joint dinner, brought any firm results, or whether Assad's fate had been discussed.
Russia's foreign and defense ministers also participated in a meeting between the two leaders.
Putin said Russia was ready to do all it could to help secure peace in Syria, which has been ravaged by the conflict.
More than 250,000 people have been killed and millions forced from their homes, sparking a mass migration of around four million refugees.
"We are ready to make our contribution not only during armed hostilities in the fight against terrorism but also during a political process," Putin said.
Assad also stressed the importance of "further political steps" and praised Russia for its military and political efforts, the Kremlin said.
"I need to say that the political steps which Russia has taken since the start of the crisis prevented the events in Syria from developing along a more tragic scenario," he said.
Putin also emphasized that the Syrian people should decide their country's fate, a thinly veiled jab at the United States and other opposition backers who insist Assad must go in any peaceful settlement.
"Based on positive results in military operations at the end of the day a long-term settlement can be achieved on the basis of a political process with the participation of all political forces, ethnic and religious groups," the Kremlin strongman said.
"And ultimately, the final word no doubt should rest solely with the Syrian people."