The head of Poland's ruling party Jaroslaw Kaczynski launched an attack on Tuesday on his arch-rival Donald Tusk, saying he should not be allowed to serve as European Council president for a second term.

 

Tusk, a former head of the center-right, pro-European Civic Platform party, served as Poland's prime minister for almost two terms before resigning in 2014 to take on the top EU job.

 

His mandate as Council president, in which he chairs EU summits, expires at the end of May 2017 though he is expected to want to stay on in the post.

 

Kaczynski, his big political rival at home who heads the conservative Law and Justice (PiS) party, said in a newspaper interview that the current PiS government would not support Tusk staying on.

 

If Tusk did, he might find himself facing charges, Kaczynski said - apparently referring to his failure as prime minister to stop the Ponzi scheme Amber Gold which shook the country in 2012. PiS dominates a parliamentary panel set up to investigate the case.

 

Despite Kaczynski's strong words, a PiS government can not stop Tusk renewing his mandate as long as a majority of EU leaders back him which seems likely.

 

Most appear satisfied with Tusk's performance and are keen to avoid more instability as the EU starts negotiations over the Britons' decision to leave.

 

But the comments highlight a deep conflict between the two rivals that could complicate Tusk's candidacy.

"The Polish government will not support Donald Tusk for the second term in the European Council," Kaczynski told the Polska The Times newspaper in an interview published on Tuesday. "Tusk is a major problem."

 

"There are investigations going on in Poland in the parliament and in the prosecutors' office that may lead to pressing some charges against him. Should such a person be the head of the European Council? I have serious doubts."

 

"His further stay in Brussels is highly risky, mainly for the European Union," Kaczynski told the paper.

 

Kaczynski holds deep personal resentment against Tusk over a 2010 plane crash in Russia in which his twin brother and then-president Lech Kaczynski was killed along with the other 95 people on board.

 

Tusk was prime minister at that time and Kaczynski believes he shares political responsibility for the tragedy.