Ukrainian President Petro Poroshenko has said Russian security services are waging a cyberwar against the country, with hackers targeting Ukrainian state institutions about 6,500 times in the past two months.

Just this month, Ukraine's Finance and Defense ministries were hit along with the State Treasury that allocates cash to government institutions. A suspected hack also wiped out part of Kyiv's power grid, causing a blackout in part of the capital.

"The investigation of a number of incidents indicated the complicity directly or indirectly of Russian security services waging a cyberwar against our country," Poroshenko said, urging his National Security and Defense Council to take protective measures on December 29.

"Acts of terrorism and sabotage on critical infrastructure facilities remain possible today."

He said the attack on the State Treasury halted its systems for several days and state workers and pensioners were unable to receive their salaries or payments on time.

Russia has repeatedly denied hacking accusations.

The Ukrainian Security Service blamed Russia for a December 2015 regional power outage, the first known power outage caused by a cyberattack anywhere. A Russian hacking group known as Sandworm was implicated.

Based on reporting by Reuters