Prime Minister Vladimir Putin on Monday vowed to reverse Russia's demographic decline and boost its population to 154 million, as he ramped up his re-election campaign in the face of protests.

In a new campaign article addressing his core constituency including employees of state companies and blue-collar workers, Putin also promised salary hikes to teachers and doctors and pledged to create a more just state.

Putin reeled off a list of social policies that he said could reverse a demographic decline and boost Russia's current population that has now dwindled to almost 143 million.

"In a global sense we are facing the risk of turning into an 'empty space' whose fate will not be decided by us," Putin said in an article published on his campaign website and mass circulation newspaper Komsomolskaya Pravda.

"If we manage to formulate and implement an effective complex people-saving strategy, Russia's population will go up to 154 million."

"The historic price of the choice between action and inaction is nearly 50 million human lives over the next 40 years," he said in the piece, his fifth campaign article since January.

After serving two consecutive presidential terms between 2000 and 2008 and a term as prime minister, Putin is seeking a third term in the March 4 presidential election.

He is however struggling with the worst legitimacy crisis of his 12-year rule, with tens of thousands taking to the streets in December and earlier this month.

Putin said one in eight Russians still lived below the poverty line, adding that the gap between the rich and the poor was too wide.

He said that by 2018 the income of university teachers, professors and doctors will stand at 200 percent of the national average, also promising 5,000 ruble ($167) stipend hikes to students.

"Every ruble going into the social sphere should 'create justice,'" Putin wrote. "The just arrangement of our society and economy is the main condition of our sustainable development over the next year."

Putin has written four articles since January on subjects including Russia's politics, economy and illegal immigration, although he has refused to take part in televised debates with other candidates.