German Chancellor Angela Merkel said Tuesday it would be a "pity" if the Russian president were to "use" the commemoration of World War II victory for visiting Crimea.

Merkel was responding to a reporter's question about media reports that Vladimir Putin could attend a May 9 military parade in his first visit to the peninsula since Russia annexed the territory in March.

German Chancellor Angela Merkel said Tuesday it would be a "pity" if the Russian president were to "use" the commemoration of World War II victory for visiting Crimea.

Merkel was responding to a reporter's question about media reports that Vladimir Putin could attend a May 9 military parade in his first visit to the peninsula since Russia annexed the territory in March.

Russian President Vladimir Putin on Monday signed new legislation introducing harsh punishments for the justification or denial of Nazi war crimes.

The legislation makes it a criminal offence to deny facts established by the Nuremberg trials regarding the crimes of the Axis powers and to disseminate "false information about Soviet actions" during World War II.

Russian President Vladimir Putin's spokesman said it would be absurd to conduct snap polls in Ukraine amid the raging violence, saying the Kremlin no longer had any influence over rebels in the country's east.

"We do not understand what elections in Kiev they are talking about in European capitals and Washington," Dmitry Peskov was quoted as saying by Russian news agencies.

President Vladimir Putin's spokesman said Friday Ukraine's offensive against pro-Russian rebels in the east dealt a final blow to a peace deal on the crisis, adding a Moscow envoy had been dispatched there to help negotiate the release of kidnapped OSCE monitors.

"While Russia is making efforts to de-escalate and settle the conflict, the Kiev regime moved combat air forces against peaceful settlements, began a reprisal raid, essentially finishing off the last hope for the feasibility of the Geneva accords," Dmitry Peskov was quoted as saying by Russian news agencies.

President Vladimir Putin will make his first visit to the Crimean peninsula since Russia annexed the territory in March, reports said Wednesday, in a move to bolster public support amid simmering tensions in Ukraine. 

Russian dailies Kommersant and Gazeta.ru reported Putin could attend a May 9 military parade marking victory in World War II in Sevastopol, which hosts the Black Sea fleet.

Pro-Russian insurgents Wednesday lifted an armed siege of a regional police headquarters in the eastern Ukrainian city of Lugansk after the chief officer agreed to resign, as Kiev said its army is on "full combat alert" against a possible Russian invasion.

A police spokeswoman said the officers inside had refused to give up their weapons to a crowd of some 1,000 pro-Moscow militants led by 30 or so armed men carrying Kalashnikov assault rifles and grenade-launchers, who had tried to storm the building overnight.

Russia and the United States stepped up their rhetoric over the spiraling crisis in Ukraine, as pro-Moscow militants shored up control of key buildings in the country's increasingly chaotic east Wednesday.

President Vladimir Putin threatened that U.S. sanctions against Moscow could harm Western energy interests in Russia, which the West blames for stoking the worst confrontation since the end of the Cold War.

New laws passed on Monday in Russia make it easier for native speakers and those who can prove they or their families have lived within the borders of the former Russian empire or Soviet Union to get citizenship.

The amendments were signed into law by President Vladimir Putin, who annexed the Russian-speaking peninsula of Crimea in Ukraine last month and has asserted his right to protect Russian speakers across the former Soviet bloc.

Russian President Vladimir Putin said on Monday he had signed a decree rehabilitating Crimea's Tatars, an ethnic group accused of collaborating with Nazi Germany and exiled under Stalin.

"I have signed a decree to rehabilitate the Crimean Tatar population of Crimea, the Armenian population, Germans, Greeks, all those who suffered during Stalin's purges," Putin told a government meeting.