Kremlin officials have confirmed the Russian leader is scheduled to meet with President Almazbek Atambayev of Kyrgyzstan in Saint Petersburg on Monday.

Putin was last seen in public on March 5, at a news conference held with Italian Prime Minister Matteo Renzi.

Since then he has cancelled several planned events, including a trip to neighboring Kazakhstan and signing an alliance with the disputed former Georgian region of South Ossetia.

Speculation over the reasons behind the 62-year-old's unusual absence from the public spotlight have ranged from questions over his health, to whether he had become a father again, and even that he had been quietly deposed.

Social network Twitter saw the hashtag #Putinumer, meaning "Putin dead", trend across the site.

Meanwhile independent broadcaster Dozhd quoted sources as saying Putin was suffering from a bout of the flu, and was recovering in his Lake Valdai residence in the country's north.

On Sunday, the Russian strongman's spokesman Dmitry Peskov dismissed all these theories as "March madness."

This week marks one year since a referendum was held on the annexation of the Black Sea peninsula of Crimea.

In a documentary that aired on Russian television on Sunday night, Putin said he had considered using nuclear forces in the occupation of the former Ukrainian territory, but "no one was in the mood to start a world war."

'New challenges and threats'

Russian state media reported on Monday that Putin had ordered the country's northern naval fleet and paratrooper units to be on full alert, as part of spontaneously-held military exercises in the Arctic.

The training is part of a move by Russia to expand its presence in the resource-rich region.

Russian Defense Minister Sergei Shoigu told state-run news agency RIA that Russia was under pressure to protect itself against new threats.

"New challenges and threats to military security require the armed forces to further boost their military capabilities.

"Special attention must be paid to strategic formations in the north," he said.

The training is to involve nearly 40,000 servicemen, more than 40 warships and 15 submarines.

The ongoing crisis in Ukraine has pushed relations between Russia and the west to breaking point, putting them at their lowest ebb since the Cold War.

Last week new allegations were made by NATO claiming the former Soviet state had been arming separatists in eastern Ukraine.

More than 6,000 people have been killed in the almost year-long battle.

an/rc (AFP, Reuters, dpa)