Former Polish President Lech Walesa says he is determined to fight a defamation case filed after he called the current president a "blockhead".
Lech Walesa is not above the law, the governing party says.
"I stick by what I said," Mr Walesa told AFP news agency. "We'll see each other in court."
Last week a report commissioned by President Lech Kaczynski criticised Mr Walesa for retaining Soviet-trained spies in post-communist Poland.
The former president replied: "We have a blockhead for president."
At the weekend the governing Law and Justice party filed a lawsuit for defamation.
Under Polish law, offending the head of state is a crime that can carry a three-year prison sentence.
"No-one in this country is above the law, not even Lech Walesa," a party spokeswoman said.
The report, published on Friday, said agents trained in the former USSR held key post in Poland's military intelligence service after the fall of communism.
In the 1980s Mr Walesa led Solidarity, the first independent mass political movement to emerge in the Soviet bloc.
He served as Poland's president between 1990 and 1995.