Shown on Kremlin-friendly media, the annual session with Putin sees the president field in real time queries submitted by Russians throughout the country.

This year's phone-in on Wednesday, which lasted nearly four hours, repeatedly faced connection problems, particularly during calls from remote regions.

"Our digital systems are right now facing attacks, powerful DDoS attacks," a Rossiya-24 presenter told Putin, after a caller from the Kuzbass region in southwestern Siberia experienced connection issues.

"Are you joking? Seriously?" Putin responded.

"Turns out we have hackers in Kuzbass," he quipped.

Russia's largest telecommunications provider, Rostelecom, confirmed the attacks to news agencies, saying that measures were being taken to "block these illegitimate activities".

Putin's spokesman Dmitry Peskov told the RIA Novosti news agency that the origin of the attacks was unclear.

Cybersecurity was one of the main topics on the agenda at Putin's summit with US President Joe Biden earlier in June.

Biden's administration in April slapped sanctions on Moscow over the SolarWinds cyberattack that targeted federal organisations and more than 100 US companies.

The United States has also accused Russia of meddling in its elections, saying the interference was carried out by either Russian security services or Kremlin-linked hackers.

The Kremlin has repeatedly denied these allegations.