Medvedev and his Bulgarian counterpart, Georgi Parvanov, met in Moscow on Thursday and discussed new oil and gas pipelines and European energy security in the wake of gas supply disruptions last month.
"Our economic cooperation has been developing dynamically and beneficially of late. Bilateral trade has almost quadrupled over the past six years," Medvedev said.
He said that the countries were implementing major projects in the energy sector that were "important not only for Russia and Bulgaria, but for the whole of Europe as well."
They include the Belene nuclear power plant Russia is building in northern Bulgaria; the South Stream pipeline to bring Central Asian and Russian gas to the Balkans and other European countries; and a pipeline project between Russia, Greece and Bulgaria to pump Russian and Caspian oil from the Bulgarian Black Sea port of Burgas to the Greek Aegean port of Alexandroupolis.
The leaders also opened the Year of Bulgaria in Russia - to mark 130 years since the countries established diplomatic relations - with a performance at Moscow's Bolshoi Theater.