"These are not going to be honest elections, but we must not relent,'' Mikhail Gorbachev, the last leader of the Soviet Union who has grown increasingly critical of Putin, said as he cast his ballot.
Golos, an independent monitoring group, said it had already registered 2,283 reports of violations nationwide.
Lilia Shibanova, the executive director of the group, told Al Jazeera there had been "a lot of abuses" in Moscow, central Russia and Baskortostan.
"On the positive side, the web cameras and transparent ballot boxes have surely helped and it is the first time we have been able to monitor the elections in Chechnya, Dagestan and the Caucasus," she said.
An interior ministry spokesperson said there had been no major violations.
Read More | "Putin 'wins' Russia's presidential election | Al Jazeera