Russia loses up to 1 trillion roubles (£20bn) a year in tax evasion schemes with a further £32bn leaving the country illicitly in 2012, senior officials have said.

The central bank governor, Sergei Ignatiev, said that "shadowy operations" to transfer money abroad were worth the equivalent of about 2.5% of Russia's annual GDP.

"This could be the payment for the delivery of drugs or other goods forbidden to bring in too Russian territory. It could be payment for illegal imports … bribes and kickbacks for civil servants," he said.

Ignatiev, who will step down in June after 11 years in the job, also said that about 50% of the illegal transfers could be tracked back to one organisation, which he refused to identify.

"Our analysis shows that more than half of these shadowy operations are carried out by firms indirectly or directly linked with each other by payments. An impression is created that they are all controlled by one very well organised group of individuals," he told Vedomosti newspaper.

Ignatiev said that bogus "one-day" companies, some registered at remote addresses to unknowing people, were often involved in illegal transactions.

People using the one-day companies, called odnodnevniki in Russian, do not pay taxes at a municipal, regional or federal level.

"Odnodnevniki firms are simply the misfortune of our economy," he said. There are 3.9m companies registered with the Federal Tax Service but only 2m are real organisations, he added.

And even of those 2m, about 11% do not pay any taxes at all and 4-6% pay only a symbolic amount of tax.

Deputy Prime Minister Igor Shuvalov said the companies were responsible for a severe drop in tax revenues. "Look at the central bank's data: the budget is down by half-a-trillion to a trillion roubles because of a link with the blossoming business of these one-day companies," Shuvalov was quoted as saying.

Russia recorded a net capital outflow of £37.2bn in 2012, down from £52.8bn in 2011.

Russian business is known for a lack of transparency. Companies have for decades used such complex holding structures that it is frequently impossible to determine the beneficial owner.

Cyprus is traditionally the offshore destination of choice for Russian firms, with the consequence that, officially, the island is the largest foreign investor in Russia.

Natalya Orlova an economist with Alfa Bank in Moscow, said Ignatiev's figures were "very big" but should be seen in the context of Russia's corrupt economy as a whole, which experts estimate as worth between 5% and 10% of GDP (around £64bn to £128bn).

Russia is seen as one of the most corrupt countries in the world, ranking 133rd out of 176 on Transparency International's Corruption Perceptions Index.