Ukraine’s Segodnya newspaper announced the death on its website and said that Nikolayev was killed near the town of Pisky.
Nikolayev, 43, was reportedly injured in the mortar attack and died in the hospital, the daily said in a statement. "He was an outstanding photographer and fully committed to his job," the statement added.
The daily’s Chief Editor Olga Guk expressed condolences to Nikolayev's family and relatives.
Ukrainian army spokesman Andriy Lysenko said that they did not have details about the incident, but acknowledged that there was shelling in Pisky on Saturday. “The threat of an offensive remains," Lysenko said.
According to the Ukrainian army, three soldiers were injured in the past 24 hours in eastern Ukraine. The army had earlier announced a drop in the attacks from pro-Russian separatists.
Meanwhile, Eduard Basurin, a military official from the self-proclaimed Donetsk People’s Republic, said 196 items of heavy weaponry had been withdrawn Wednesday and 180 others would also be pulled out. The Organization for Security and Co-operation in Europe did not confirm the withdrawal.
A cease-fire was signed between government forces and pro-Russian separatists in the Belarus capital, Minsk, on Feb. 12, which included the withdrawal of heavy weaponry from combat areas; withdrawal of all foreign-armed formations; and release of all hostages and unlawfully detained persons, as well as political reforms and decentralization in eastern Ukraine.
More than 5,300 people have been killed and 12,200 others have been injured in eastern Ukraine since mid-April last year in the ongoing conflict, according to the UN high commissioner for human rights.