The centre-right government of the European Union's poorest member managed to limit bribery in the first two years of its term in 2009 and 2010, but the effort has since lost momentum, and corrupt practices are on the rise, a survey by independent think-tank Centre for the Study of Democracy (CSD) showed.
Corruption and organised crime blight Bulgaria 20 years after the end of communist rule, putting off investors, hindering growth and delaying its entry into the EU's Schengen agreement, which allows passport-free travel between countries.
One out of every four Bulgarians who dealt with doctors, police officers, customs officials or judges in 2011 offered money, a gift or a favour to see his problem solved efficiently, the survey's data showed, compared with one out of five in 2010.
"The bribe-giving level is two to three times higher than the average for the European Union. The number of the bribes shows the problem is rather systemic for the society," said Alexander Stoyanov with Sofia-based CSD.
The centre, a leading anti-graft non-government organisation, has conducted corruption surveys since 1998.
Monday's survey also provided an index of business corruption that showed a decline, however, as more entrepreneurs and companies refused to pay bribes to government officials for deals and other services.
Bulgaria ranks fourth in the EU in terms of corruption pressure, after Romania, Lithuania and Slovakia in 2011, a Eurobarometer poll showed.
Sofia has yet to install proper monitoring and prosecuting units and reform its slow and inefficient judiciary to effectively combat petty and high-level corruption.
Although the government of Prime Minister Boiko Borisov declared an intention to sever links between high level officials and organised crime bosses, it has failed to jail a single senior official for corruption.