A Russian state television reporter was killed in Ukraine and his colleague is missing after their position was shelled in clashes between Ukrainian forces and pro-Russian separatists near the eastern city of Luhansk, the Rossiya-24 channel said on Tuesday.
Igor Kornelyuk, 37, died in hospital after coming under fire while covering heavy fighting that began overnight when Ukrainian forces made a push to enter the main city in Ukraine's easternmost province, near the border with Russia, it said.
"He was critically wounded in a mortar attack," the channel said on its website. "The fate of the sound man, Anton Voloshin, is unknown."
The Russian Foreign Ministry said Kornelyuk's death demonstrated the "criminal nature" of Ukraine's military operation against pro-Russian rebels and urged authorities in Kiev to investigate.
The loud crack of heavy artillery is audible on shaky footage shot by cameraman Viktor Denisov, who survived the attack on a rebel roadblock where they were filming.
As smoke clears, a fighter is shown dragging a wounded man off the road into the bushes.
"I got lucky," Denisov told the Russian LifeNews website. "One of the shells landed on them ... I ran the other way when the area came under fire."
A spokeswoman for separatists in Luhansk said fighting was still too heavy to allow a search for Voloshin.
Earlier, about 30 Ukrainian servicemen were wounded in fighting with pro-Russian separatists near Ukraine's eastern border with Russia, the border guard service said.
It said separatist fighters had fired mortar bombs on government forces and border guards during the night near the city of Luhansk. It gave no details of any casualties among the rebels, who oppose central rule by Kiev's pro-Western leaders.
The separatists say government forces have been shelling their positions this week, including around the city of Slaviansk, scene of some of the heaviest fighting since the uprising began in the Russian-speaking east in April.
President Petro Poroshenko has ordered government forces to retake control of the border from the rebels after Kiev and the United States accused Russia of sending fighters and weapons, including tanks, across the frontier. Moscow denies this.
Poroshenko said on Monday that government forces had already re-established control of a more than 250-km (156-mile) stretch of the almost 2,000-km (1,240-mile) land border with Russia.
Kiev says 125 Ukrainian servicemen have been killed since the start of a military operation to defeat the separatists in May. Scores of separatist fighters have also been killed in fighting, as well as an unknown number of civilians.
The crisis in Ukraine erupted late last year when protesters took to the streets against a president sympathetic to Moscow. He was overthrown in February, Russia annexed the Crimea region in March and the uprising in the east began in April.
Gas
Ukraine said on Tuesday it was treating an explosion on a pipeline carrying Russian natural gas to the rest of Europe as a possible "act of terrorism".
"Several theories of what happened are being considered including the key theory - an act of terrorism," Interior Ministry Arsen Avakov said in a statement after the blast in central Ukraine, which did not disrupt the gas flow.
This as, a source at Russia's top natural gas producer Gazprom said an explosion at a transit pipeline in central Ukraine has not cut Russian gas exports to Europe as the fuel is flowing through a parallel pipe.
Also on Tuesday, British Foreign Secretary William Hague said that Gazprom's decision to cut gas supplies to Ukraine over a pricing dispute undermined Russia's reputation as a reliable energy supplier.
"We obviously regret Gazprom's decision to do this and I think such decisions damage the credibility of Russia in supplying energy elsewhere across Europe," Hague told parliament.
In the same regard, Norway's Statoil could increase gas supplies to the European Union but would not be able to replace Russian gas, CEO Helge Lund said on Tuesday, a day after Moscow cut off supplies to Ukraine over a price dispute.
"We can increase somewhat but we cannot replace Russian gas," Lund told reporters on the sidelines of an energy conference when asked if the company could boost supplies to substitute exports from Russian company Gazprom.
He did not provide any figures.
Statoil is the second largest supplier of natural gas to the European market, with a market share of around 14 percent, according to company data.
Gazprom's supplies to Europe including Turkey rose 16 percent to a record high of 161.5 billion cubic metres (bcm) last year from 138 bcm in 2012 while Norway's fell by 5 percent to 102.5 bcm.