A Republican political consultant linked to Paul Manafort and Cambridge Analytica has admitted to funneling $50,000 from a Ukrainian oligarch to Donald Trump’s presidential inauguration committee.

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Sam Patten used the money to buy tickets for the oligarch and a Russian associate to Trump’s inauguration in January 2017, according to a plea agreement made public on Friday. The inauguration fund was not allowed to accept money from foreigners.

The disclosure came as Patten pleaded guilty to illegally lobbying in the US for pro-Russia politicians from Ukraine. As part of his plea deal, he agreed to cooperate with Robert Mueller, the special counsel investigating links between Donald Trump’s campaign team and Russian interference in the 2016 election.

Patten, 47, admitted causing the Ukrainian funds to be paid to the inauguration committee, and to lying to a Senate committee investigating Russian interference in an attempt to cover this up. He was not charged for these actions.

He pleaded guilty to one count of working as an unregistered agent for the oligarch’s Ukrainian political party, Opposition Bloc, which also employed Manafort, the former chairman of Trump’s 2016 campaign. Patten was released on bail by judge Amy Berman Jackson following a hearing in Washington.

The charge was brought by the US attorney’s office in the capital, which took over the case following a referral from Mueller’s office. The court filings indicated that Patten had been in discussions with Mueller’s office for at least three months.

A spokesman for the US attorney’s office said the charge against Patten was a felony punishable by a maximum of five years in prison and also carried potential fines. Stuart Sears, an attorney for Patten, declined to comment.

A spokeswoman for Thomas Barrack, the chairman of Trump’s inauguration committee, did not respond to requests for comment.

The filings recounted how Patten formed a consulting company in the US with Konstantin Kilimnik, a Russian political operative with alleged ties to intelligence services. Kilimnik, identified as “foreigner A” in the filings, has also worked extensively with Manafort, who was a consultant to Opposition Bloc in Ukraine.

After discovering foreigners were barred from giving money to the inauguration, Patten enlisted another American to buy four tickets. The oligarch paid $50,000 to Patten and Kilimnik’s company from an account in Cyprus. Patten then wrote the American “straw purchaser” a $50,000 check and the American used these funds to buy the tickets the following day. The tickets were used by Patten, Kilimnik, the oligarch and another Ukrainian.

Patten then lied about this arrangement during testimony to the Senate intelligence committee in January 2018, he admitted on Friday. He failed to provide requested documents, gave misleading evidence and then after his interview deleted files relating to his work for the Ukrainians.

In all, according to the court documents, Patten’s firm was paid about $1m for advising Opposition Bloc and lobbying US politicians on its behalf. Patten worked to set up meetings for Kilimnik and the oligarch with state department officials and members of Congress, including senators on the foreign relations committee and House members on the foreign affairs committee.

Patten admitted that he knew he was required to register as an agent for a foreigner but failed to do so after the Ukrainian oligarch said “he did not want them to” until an unspecified future date.

Patten also drafted opinion articles for the Ukrainian oligarch and succeeded in having at least one published by a national American media outlet in February 2017.

The Ukrainian figure and media outlet were not identified in the charging documents. A pro-Trump article was published by US News & World Report in February 2017 under the byline of Serhiy Lyovochkin, an Opposition Bloc MP who was a senior official in Ukraine’s former pro-Kremlin administration.

Enxhi Myslmi, a spokeswoman for US News & World Report, said: “To our knowledge, no one at US News has been contacted by law enforcement regarding the publication of this piece.”

Lyovochkin’s office declined to say if it believed he was the oligarch described in the court documents. In an unsigned email, it said: “Mr Lyovochkin was indeed invited to the inauguration and had the honor to attend. At the same time, he did not pay for that.”

Facebook Twitter Pinterest Paul Manafort, seen outside court in Washington in June. Photograph: Jonathan Ernst/Reuters

Earlier this month, Manafort was convicted on eight counts of bank and tax fraud arising from the Mueller investigation. During the trial, a former colleague testified that Manafort received payments from Lyovochkin and disguised them as loans to avoid paying tax.

Kilimnik is charged alongside Manafort in a separate criminal case brought in Washington by Mueller.

Patten also carried out work for Cambridge Analytica, the now-defunct consultancy that is under scrutiny for its work on Trump’s 2016 election campaign. A page on Patten’s website that has since been removed said he “worked with one of London’s most innovative strategic communications companies to introduce new technologies and methodologies” during the 2014 US election.

During an interview last year with a British academic researcher, Patten said: “I’ve worked in Ukraine, Iraq, I’ve worked in deeply corrupt countries, and [the American] system isn’t very different.”