KIEV, Sept. 8 – Prime Minister Yulia Tymoshenko must show up at the Prosecutor General’s Office on Thursday for questioning in connection with the investigation of the 2004 poisoning of Viktor Yushchenko, the office announced Monday.

This is the first time the office has disclosed plans to question Tymoshenko as part of the investigation, which tries to solve one of the biggest mysteries in modern history of Ukraine: Who poisoned Yushchenko, then the opposition presidential candidate, in September 2004?

The poisoning nearly killed Yushchenko, a pro-Western figure who ran against then-Prime Minister Viktor Yanukovych, a candidate backed by the Kremlin, in the runoff to the presidential election.

Yushchenko survived the poisoning after an intensive treatment at a private hospital in Vienna in September 2004, but his face has remained disfigured and deeply scarred with what has been later confirmed as severe dioxin poisoning.

Tymoshenko, Yushchenko’s ally in the 2004 election, would mostly likely have become the leader of the opposition in Ukraine and would probably have gotten elected president in case of Yushchenko’s death, analysts said.

This is the second time that a former Yushchenko ally is being summoned up for questioning as part of the investigation. In July, David Zhvania, who arranged the dinner with top security officials at which Yushchenko is believed to have been poisoned, refused to answer questions, calling it a “show.”

Zhvania, a sponsor of People’s Self-defense group, part of Our Ukraine-People’s Self-defense alliance, has been closely cooperating with Tymoshenko over the past year.

Volodymyr Satsiuk, a top security service official who hosted the dinner and the key suspect in the poisoning case, has been hiding in Moscow. Satsiuk recently was granted Russian citizenship, which makes his extradition to Ukraine impossible.

Satsiuk has recently been closely cooperating with Tymoshenko, acting as a liaison between Russian security services and the Tymoshenko group, according to Stanislav Belkovskiy, a well-connected Moscow—based political analyst.

Russia, one of the three countries capable producing toxic dioxin, has been refusing to cooperate with Ukraine on the poisoning case.

Unlike the U.S. and Britain, the two other countries on the list, Russia for years has been refusing to provide its dioxin samples to check against those found in Yushchenko’s blood.

But last year Russia suddenly admitted it had produced the same kind of dioxin that had been used to poison Yushchenko, although such production had been discontinued.

The latest developments come as the coalition backing the Tymoshenko government collapsed last week after Yushchenko pulled his party following disagreement with the prime minister over Ukraine’s foreign policy.

Tymoshenko, who Monday confirmed she was due to answer the questions on Thursday, said her telephone conversations had been tapped by security service.

“They have been following me 24 hours a day for many months,” Tymoshenko said at a press conference. “I have a number of telephone calls tapped. I have no immunity.”

Hanna Herman, a spokesman for the opposition pro-Russian Regions Party, which has been recently assembling anti-Yushchenko alliance in Parliament, said the investigation has been used to put pressure on Tymoshenko.

“The summoning up of Tymoshenko for the questioning to the Prosecutor General’s Office in the middle of the standoff between the president and the prime minister resembles the political persecution,” Herman said.

The office of Yushchenko last month accused Tymoshenko of secretly working to promote Russian interests in Ukraine in exchange for $1 billion financing of her campaign to become the next president of Ukraine.

Tymoshenko dismissed the allegations. (tl/ez)