KIEV, Ukraine (AP) — A new indictment against former Donald Trump campaign chief Paul Manafort focused a spotlight Saturday on uncovering the former European leaders who prosecutors contend were secretly paid by Manafort to lobby on behalf of Ukraine.

The U.S. indictment handed up Friday by a grand jury doesn't name the European politicians, although it notes they worked in coordination with Manafort, his deputy Rick Gates and two Washington lobbying firms — the Podesta Group and Mercury Public Affairs — to lobby U.S. officials and lawmakers.

At least four leaders — former Italian Prime Minister Romano Prodi, former Austrian Chancellor Alfred Gusenbauer, former Polish President Aleksander Kwasniewski and former Ukrainian President Viktor Yushchenko — were named last year in public filings by the two lobbying firms. The firms said the politicians were involved in U.S. speaking events and meetings with U.S. lawmakers and others to promote Manafort's client at the time, Ukraine's pro-Moscow president, Viktor Yanukovych.

The filings did not disclose any payments to the former officials, and it's unclear if they are the same politicians referenced in the U.S. indictment.

U.S. law requires people who are lobbying U.S. officials on behalf of foreign governments or political parties to register, and a Justice Department database doesn't show that those former European officials did.

But it's unclear from the U.S. indictment how much the former European politicians knew about their funding or if they could be covered by some legal exemption.

The lobbying by the European political figures, identified in the indictment as the "Hapsburg Group," allegedly took place in 2012-13, when Ukraine was moving toward closer integration with the European Union. But the indictment doesn't formally charge any of the leaders or refer to them as co-conspirators of Manafort and Gates.

None of the four politicians responded to requests for comment Saturday from The Associated Press but three of them were quoted as denying the reports.

Gusenbauer told the Austrian national news agency APA that he never acted on Yanukovych's behalf.

"I never undertook activities for Mr. Yanukovych" or his party, the news agency quoted Gusenbauer as saying. He said his interests in 2012 and 2013 were in bringing the nation of Ukraine closer to Europe.

"In public events in Paris, Brussels and Berlin, I advocated for the European Union concluding an association agreement with Ukraine," he said.

The press office for Prodi, the former Italian premier and European Commission president, denied that he was ever involved or paid by a secret lobbying group.

Prodi "never took part in any kind of secret activity, let alone in secret lobbying groups, nor has he ever received compensation for this kind of activity," said the statement, carried by the Italian news agency ANSA.

The statement said "Prodi has long worked so that Ukraine's growing nearer to Europe can become concrete" and added that his activity "was public and thus easily traceable."

Kwasniewski was quoted as saying he had no financial or political agreements with Manafort and was not familiar with the term "Hapsburg Group."

The leading Polish news outlet Onet quoted him as saying that he knows Manafort, having met him in 2012 when he and Patrick Cox, a former European Parliament president from Ireland, led a mission to Ukraine to try to persuade Yanukovych to release his rival, former Ukrainian prime minister Yulia Tymoshenko, from prison.

"We met several times, with the hope that Manafort would help convince Yanukovych" to release Tymoshenko, Kwasniewski was quoted as saying. "I have not seen him since November 2013, when Yanukovych refused to sign the association agreement with the EU."

"No money came into play. I did not have any financial or political agreements with him. This is some kind of misunderstanding," he said.

He said there were many debates and conferences on Ukraine in 2012 and 2013, and he took part in them, "sometimes with Prodi, sometimes with Gusenbauer."

"Of course, we took fees. Maybe Manafort paid for them through his companies? But these were public, open debates," Kwasniewski was quoted as saying.

A Ukrainian lawmaker, meanwhile, told the AP on Saturday that a former Austrian chancellor was among the European politicians secretly paid to lobby for Ukraine.

Serhiy Leshchenko, who says he helped uncover off-the books payments from Yanukovych to Manafort, said he saw the information about a former Austrian chancellor in a ledger of payments to Manafort.

"I don't remember the name, but I remember the position," Leshchenko said in an interview.

Leshchenko noted that Gusenbauer had lobbied for Ukraine when Yanukovych was in power and said his activities clearly were in the interests of Yanukovych's Party of Regions and could be seen as a way "to launder the reputation of Yanukovych in Europe."

"There were a number of events that took place in Europe with the engagement of Mr. Gusenbauer and other former European politicians to present Mr. Yanukovych in better lights in Europe," he said. "Mr. Prodi was engaged in this activity as well."

In a statement, Mercury partner Mike McKeon said his firm was misled by Gates, who pleaded guilty Friday in the case, about the nature of the work.

Gates "admitted that he didn't tell the truth to the government and didn't tell the truth to our lawyers when he spoke to them about this project," McKeon said.

"While he and others involved with this matter may have acted criminally and tried to hide it, we have acted appropriately, following our counsel's advice from the start," he added.

McKeon said the firm is cooperating with special counsel Robert Mueller's investigation.

A person familiar with the lobbying effort said that Podesta Group employees were not aware of any payments to former European politicians as described in the indictment, learning of the allegations only Friday when prosecutors made them public. The person spoke on condition of anonymity because they weren't authorized to speak publicly on the matter.

The EU integration issue eventually led to Yanukovych's ouster.

He had been expected to sign an "association agreement" with the EU that would allow for a freer movement of goods and was seen as a step toward eventual EU membership.

Russia, however, strongly opposed any tilt to the west by Ukraine.

Under pressure from Russia, Yanukovych backed away from signing the EU agreement at the last minute, sparking a protest in Kiev in 2013. Police brutally dispersed the demonstrators, which galvanized opponents to call larger anti-government rallies that developed into a huge, ramshackle protest encampment in the center of Kiev, the Ukrainian capital.

The protests persisted for months and descended into violence, which climaxed with the February 2014 shooting deaths of scores of people by still-unidentified snipers. Faced with growing chaos, Yanukovych quickly fled the country and ended up in Russia.

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Jim Heintz in Moscow, Geir Moulson in Berlin, Chad Day in Washington, Vanessa Gera in Warsaw, Frances D'Emilio in Rome and Yuras Karmanau in Minsk, Belarus, contributed to this story.