(CNN) A Democrat on the House intelligence committee flew to Cyprus last week as part of the panel's broad investigation into allegations that Russian operatives and top aides on President Donald Trump's campaign colluded to influence the US election.

"You go to Cyprus because that's where Russians launder money," said Rep. Mike Quigley, D-Illinois, in explaining the reason for his trip.

The Mediterranean island nation has become a part of the sprawling probe following an Associated Press report last month that said as part of an anti-corruption investigation into former Trump campaign chairman Paul Manafort's work in eastern Europe, Treasury officials obtained information regarding financial payments Manafort may have received through Cypriot banks.

The AP story cites a person familiar with the matter who was not authorized to speak publicly.

Manafort's finances and consulting work are drawing attention as Ukrainian officials try to determine whether he received improper payments as part of their corruption investigation into ex-President Victor Yanukovych -- Manafort's former client. US authorities also are investigating possible Ukrainian corruption and any role Manafort might have played in Russia's meddling in the 2016 presidential election.

In addition to reporting on Manfort's financial transactions in Cyprus, the AP reported earlier this week that a firm he headed received $1.2 million in off-the-books payments for work done in support of a pro-Russian political party in Ukraine.

Manafort strongly denies any wrongdoing in connection with his work for Trump and foreign officials. He has offered to testify in the House and Senate intelligence committees' investigations into Russia's election interference.

"Like many companies doing business internationally, my company was paid via wire transfer, typically using clients' preferred financial institutions and instructions," Manafort said in a statement to CNN last Friday.

A source close to Manafort also told CNN Manafort did not choose to use any banks in Cyprus, but his clients made that choice. The source said Manafort used the US bank Wachovia to receive payments.

Quigley spent two days in Cyprus this week with staff investigators from the House Intelligence Committee, but no other members of the panel. He declined to discuss who he interviewed or which documents he might have viewed.

Broadly speaking, Quigley said the trip was critical to understanding how Russians move money.

"Understanding how that works is important to understanding how they fund their regime, what are the motivations for laundering money ... " Quigley said. "You launder money to avoid taxes, to avoid worldwide sanctions."

In an interview on CNN's "Erin Burnett OutFront" a week after the trip, Quigley declined to go into detail about what he might have learned or if he discovered any wrongdoing.

"I can't reveal what I was told in confidence," Quigley said.

However, he still implored people to focus on questions related to Cyprus.

"This is where a lot of money laundering takes place," Quigley said. "This is where the Russians act, and this is where key figures in the investigation have played as well."

"It has been known as Russia's laundromat" @repmikequigley details trip to Cyprus for #Trump-Russia investigation https://t.co/ytmtJn1CEY — OutFrontCNN (@OutFrontCNN) April 20, 2017

Manafort's personal finances -- including a series of multimillion-dollar real estate purchases from 2006 to 2012 while he was working with Ukrainians and a Russian industrialist -- have drawn increased scrutiny.

House and Senate investigators have not said yet when they plan to call Manafort to testify, but the top Democrat on the Senate intelligence committee, Virginia Sen. Mark Warner, has said it may take some time for investigators complete research before bringing in high-profile targets.

Quigley said last week he is likely to travel overseas again as part of the investigation, but no details have been firmed up yet. Democratic members on the House Russia investigation have taken to specializing in certain aspects of the issue and focusing their research and questioning in specific areas.

Quigley would not say what his specialty is. However, during the House intelligence committee's first public hearing last month, Quigley focused his line of questioning on how people can unwittingly be co-opted by Russian agents posing as businesspeople in Eastern Europe.

Quigley also traveled to Ukraine in February he and Senate Minority Whip Dick Durbin met with Ukrainian leaders. Quigley said he was able to do some investigating while there, but did not disclose any details.