European Council President Donald Tusk | Emmanuel Dunand/AFP via Getty Images Tusk faces Polish tax probe Poland’s ruling party has been accused of trying to weaken Tusk ahead of next year’s presidential election.

WARSAW — European Council President Donald Tusk faced a parliamentary grilling in Warsaw on Monday over allegations that he didn't do a good job of preventing VAT fraud while Polish prime minister from 2007 to 2014.

Marcin Horała, chair of the committee investigating VAT issues and a member of Poland's ruling Law and Justice (PiS) party, said there was "at least a suspicion" that Tusk "either did not sufficiently supervise the services reporting to him or did not take appropriate action that could protect the state budget from VAT fraud."

The party accuses Tusk's government of allowing 250 billion złoty (€58.8 billion) to be stolen from the government budget due to VAT hoaxes.

Tusk fired back that he worked to clamp down on the problem and accused PiS, then in opposition, of hampering efforts to make VAT fraud more difficult.

"I have no illusions. I'm not here because I believe in your good intentions in getting to the truth," Tusk told Horała in one of several testy exchanges. "I'm here because I respect the institutions of the Polish state."

He also lambasted the committee for only focussing on the time that his Civic Platform party was in power, ignoring the PiS governments that ran the country from 2005 to 2007 and after 2015.

VAT fraud is an EU-wide problem, with the European Commission estimating that in 2016, member countries lost €147.1 billion, or 12.3 percent of expected VAT revenues. Poland is at the upper end of the EU scale when it comes to fraud, although countries like Italy, Greece and Romania have higher rates. Under the PiS government, the rate of fraud has fallen.

Tusk has been called before several parliamentary inquiries and court hearings, something his supporters see as part of a PiS effort to undercut his authority in the country in case he decides to run in presidential elections next year, once his term as Council president ends.