Russian President Dmitry Medvedev lashed out Friday at what he called shoddy efforts to revive Russia's economy, the latest in a series of statements seen by some as veiled criticism of Prime Minister Vladimir Putin. "We're working very slowly, just unacceptably slowly for a crisis," Medvedev told federal and regional economic officials in the Siberian city of Irkutsk. "We need to focus on diversification of the economy, development of infrastructure and strengthening of the financial system." Medvedev did not mention Putin or the Cabinet, which Putin heads. But as prime minister, Putin is in charge of setting and implementing economic policy. Medvedev's comments may feed speculation that the strains of the global economic turmoil - which hit Russia just months after Putin guided Medvedev into the presidency - could create fissures in what both men call their governing "tandem."