A key witness in special counsel Robert Mueller's probe into Russian connections to the Trump campaign is a convicted pedophile, an official in the Czech Republic confirmed on Wednesday.

George Nader was convicted by Prague's Municipal Court of 10 cases of sexually abusing minors and sentenced to a one-year prison term in May 2003, said Marketa Puci, a court spokeswoman.

She said the crimes occurred between 1999 and 2002.

Nader is an international fixer whose long history included intrepid back-channel mediation between Israel and Arab countries - and a 15-year-old pedophilia conviction in Europe that has not been previously reported.

Puci, the court spokeswoman, said Nader was convicted of "moral corruption of minors, sexual abuse and impairing morals," after abusing underage boys.

In one case, Nader requested oral sex from a 14-year-old in a room at the Hilton Hotel in Prague, Puci said.

After the boy refused, Nader masturbated in front of the boy and paid him 2,000 koruna - worth about 100 US dollars today, she said.

The verdict cites other examples of Nader providing money, jewelry, cellphones, clothes and accommodation for sexual services.

The AP was able to see a copy of the verdict, which gives Nader's birthdate as May 15, 1959.

Nader was separately accused in Washington, D.C., of child pornography infractions in 1985, but those charges were later dropped.

A criminal docket sheet obtained by the AP shows the same birthdate for Nader.

Two people with knowledge of the case say it involved the same Nader now cooperating with Mueller.

Puci said it wasn't clear how much of the one-year sentence Nader served in the Czech Republic. He was ordered expelled following his time served.

Nader was stopped by Mueller's investigators on his way to Mar-A-Lago a few days before the one-year anniversary of President Donald Trump's inauguration.

He later agreed to cooperate with Mueller's investigation, said the people with knowledge of the case as it pertains to Nader. They weren't authorized to speak publicly on the case and demanded anonymity.

Mueller, whose team has spent the last 10 months investigating possible Trump-related wrongdoing connected to Russia, is interested in high-level get-togethers Nader participated in after the presidential election, according to three people familiar with the case.

Nader's legal problems in Prague appear unrelated to his role in Mueller's probe in the United States. But they contribute to the portrait of a man who has led a shadowy existence as a go-between across numerous Middle East capitals and who gave testimony to Mueller's Washington grand jury earlier this month.

Nader had worked in recent times as an adviser to bin Zayed, one of the most powerful men in the Middle East, according to people who know Nader. The questioning of Nader in the Mueller probe suggests possible interest in UAE relations with Trump's transition team or his administration.

Kathy Ruemmler, who previously served as White House counsel to President Barack Obama, is among the lawyers representing Nader. She declined to answer questions about her client.

But Sandeep Savla, another lawyer for Nader, said: "This is nothing more than an orchestrated, disgusting scheme by those who are trying to intimidate Mr. Nader into silence. It won't work. Mr. Nader will continue to answer truthfully questions put to him by the special counsel."

Prague - 14 March, 2018

1. Various of Prague Municipal Court Spokesperson, Marketa Puci, holding court verdict and sentence

2. SOUNDBITE (Czech) Marketa Puci, Prague Municipal Court Spokesperson:

"I'm holding a verdict by which an American citizen, George Nader, together with Czech offenders was in 2003 convicted, for crimes that I will now read to you. The court sentenced him to one year in prison and to an indefinite deportation."

3. Shot of first page of court verdict and sentence reading (Czech) "Judgement on behalf of the republic"

4. SOUNDBITE (Czech) Marketa Puci, Prague Municipal Court Spokesperson:

"According to the then valid law, Mr Nader was convicted of moral corruption of minors, sexual abuse and impairing morals."

5. Shot of first page of court verdict and sentence reading (Czech) "Judgement on behalf of the Republic"

6. SOUNDBITE (Czech) Marketa Puci, Prague Municipal Court Spokesperson:

"At that time was (the victim) was 14-years-old. He (Nader) requested oral sex and after the boy refused, he with the boy's consent, pulled out his private parts and masturbated in front of him and for that Mr Nader paid the boy 2000 Koruna. And there have been 10 similar cases like this."

7. Portion of court verdict and sentence with George Nader's name on it and stating he is a citizen of the United States