The world has plunged into a "new Cold War", the Russian premier said Saturday, as East-West tensions over Ukraine and Syria took center-stage at a gathering of world leaders in Germany.

"We have slid into a new period of Cold War," Prime Minister Dmitry Medvedev told the audience at the Munich Security Conference.

Russia's economic sanctions against Turkey over its downing of a Russian warplane could hurt the Turkish economy in several areas from fruit to tourism, even if the initial impact is likely to be limited.

Turkey and Russia have enjoyed burgeoning trade ties in recent years despite disagreements on a number of political issues from Moscow's annexation of Crimea from Ukraine to the more than four-year old civil war in Syria. 

Japanese Prime Minister Shinzo Abe on Monday criticized his Russian counterpart Dmitry Medvedev's weekend visit to disputed islands, aggravating a long-running dispute over the archipelago.

The visit "conflicts with Japan's position and hurts the feelings of the Japanese people. It is extremely regrettable," Abe told a parliamentary panel when asked about the trip.

Russian Prime Minister Dmitry Medvedev landed Saturday in the Kuril islands, prompting a swift rebuke from Tokyo, which claims sovereignty over the northwest Pacific archipelago in a long-running dispute.

Medvedev visited Iturup, one of four islands in the chain that lies off Russia's far eastern coast and just north of Japan, Russian media reports said.

Russian President Vladimir Putin will meet Palestinian leader Mahmoud Abbas in Moscow on Monday where the issue of Middle East peace talks will be raised, Russian authorities announced Thursday.

"The two leaders will hold talks concerning key aspects of Russian-Palestinian relations and their future, with particular attention on the trade, economy and humanitarian sectors," the Kremlin said in a statement.

Ukraine must pay for Russian gas being supplied to rebel areas in the country's war-torn east, Russian Prime Minister Dmitry Medvedev said Friday, raising the possibility of another gas dispute in the midst of winter.

Russian gas giant Gazprom began direct deliveries to separatist areas on Thursday in addition to other areas of Ukraine after Kiev temporarily cut supplies.

President Vladimir Putin accused his US counterpart Barack Obama of a hostile approach towards Russia, warning in a Cold War-style tirade that Moscow would not be blackmailed by the West over Ukraine.

Putin fired off his combative comments shortly before he arrived amid tight security to a red carpet welcome in Belgrade, seeking to cement Russia's influence in its loyal European ally.

Russian Prime Minister Dmitry Medvedev thinks a reset in relations between Moscow and Washington is "impossible" while punishing Western sanctions remain in force, he said in an interview aired by U.S. TV Wednesday.

Medvedev blasted U.S. and EU measures imposed on Russia over its role in the Ukraine crisis as "absolutely destructive" and "stupid" and said there was no chance of mending ties with the White House while they were in place. 

Ukrainian President Petro Poroshenko visited a flashpoint eastern city Monday where sporadic fighting has rattled a three-day-old ceasefire between government and rebel forces.

The highly-symbolic trip to the strategic port of Mariupol came just as EU officials called a new meeting to decide on fresh sanctions against Moscow should the truce fail.

Hackers broke into Russian Prime Minister Dmitry Medvedev's Twitter account on Thursday, tweeting his resignation and criticizing President Vladimir Putin.

"I'm resigning. I'm ashamed of the government's actions. Forgive me," said Medvedev's Russian-language Twitter account.