(BRUSSELS) - The head of Europe's anti-fraud agency has backed calls to establish a public prosecutor's office to probe and prosecute crimes committed against the European Union's financial interests.

Giovanni Kessler, director general of the EU's anti-fraud office OLAF, told AFP the mooted public prosecutor would be a "natural evolution" which would allow for "fully fledged criminal investigations."

OLAF, which was established in 1999, has the power to investigate fraud and corruption in EU institutions. However, it must then hand over evidence gathered to national prosecutors in the EU's 28 member states.

Kessler, a former Italian magistrate, said the replacement of OLAF by a fully independent public prosecutor would amount to a "culturally" big change but it would be a more effective way of prosecuting transnational crime in Europe.

"Now, cases are addressed by several prosecution services in Europe, but they have to go to mutual assistance and so on, and it takes a lot of time and resources," said Kessler, who spoke this week ahead of the release of OLAF's annual report.

OLAF has attracted criticism under Kessler's stewardship amid concerns that the crime-fighting body, which comes under the responsibility of the European Commission, was too close to the institution it often investigated.

OLAF's 2012 investigation into the EU's former Health Commissioner John Dalli, which led to Dalli's resignation over allegations of collusion with the tobacco industry, notably was singled out for criticism by the European Parliament.

OLAF's own supervisory committee even suggested Kessler had exceeded the agency's powers.

OLAF's annual report, released Tuesday, said that in 2013 OLAF conducted a record number of investigations, an increase of 58 percent when compared to OLAF's 2009 workload.