(BRUSSELS) - Poland's President Lech Kaczynski took his power feud with Prime Minister Donald Tusk to Brussels Wednesday, chartering a jet to attend a summit after his rival barred him from using an official plane.

Polish news channel TVN24 put the cost of hiring the Boeing 737 from Poland's flag-carrier LOT at 140,000 zlotys (40,000 euros, 55,000 dollars) in a dramatic and costly escalation of their long-running battle.

On arrival at the venue of the EU summit, Kaczynski, an arch eurosceptic, was allowed to enter despite not having the requisite special gold badge -- he was given one upon entry.

He then sat next to Tusk at the summit table at the start of the official talks which are scheduled to last until Thursday. "We are all somewhat confused, but we'll have to live with it somehow," Tusk told reporters.

Kaczynski's camp denied there was anything untoward in his attendance even though he is not part of the government.

"For the remainder of the summit the president will attend sessions focused on the EU's relations with Russia, Ukraine and on evaluation of the implementation of the Georgia peace plan negotiated by President Sarkozy," Kaczynski's aide Piotr Kownacki told AFP. He also said Kaczynski expected to hold unofficial talks with French President Nicolas Sarkozy.

The two Poles are involved in a long-running battle for influence and power that was stoked by a bitter 2005 presidential election which Tusk narrowly lost to Kaczynski.

The two were then thrown into an unhappy working relationship when Tusk won a general election in October 2007, ousting the government of the president's conservative identical twin Jaroslaw Kaczynski.

The Polish constitution gives the prime minister priority in steering the country's foreign policy, but Kaczynski has battled to set the agenda and has continued to attend summits of the European Union, which Poland joined in 2004.

The Kaczynski twins gained a reputation as troublemakers at EU summits -- they argued they were simply defending Poland's interests -- and Tusk has tried to mend fences since coming to power.

On Monday, Tusk ruled out Kaczynski's participation in the Brussels meeting of the European Council, which groups the heads of government of the EU's 27 member states.

The session is focused on the EU's response to the global financial crisis and its strategy to fight climate change.

Kaczynski and Tusk had also battled over an EU summit last month on Russia's conflict with Georgia, before the premier gave way and they both attended.

But Tusk had drawn a red line this time, saying Monday he would not brook "permanent breaches" of the constitution.

Polish media have suggested that Kaczynski's actions are not only part of his feud with Tusk's government but also may be an attempt to stop former Polish president and Solidarity era legend Lech Walesa from joining a high-level commission on the future of the EU.

On Thursday, the summit is due to approve the commission's members -- unless any member state blocks it.

Kaczynski said Wednesday that while he was not enthusiastic over Walesa's candidature, he informed Tusk he would not raise the issue at the summit.

The Kaczynski twins and Walesa were once allies in Poland's anti-communist Solidarity movement, led by the latter, but fell out after the fall of the regime in 1989.

Poles are fed up with their leaders' squabbling, according to surveys published Wednesday, with 85 percent of those polled by the PBS institute and 77 percent by agency GfK saying the sparring tarnished Poland's image.

PBS found that 83 percent of Poles were ashamed, with 63 percent saying Tusk was right and 26 percent backing Kaczynski.

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