American law enforcement and intelligence agencies are examining intercepted communications and financial transactions as part of a broad investigation into possible links between Russian officials and associates of President-elect Donald J. Trump, including his former campaign chairman Paul Manafort, current and former senior American officials said.
The counterintelligence investigation centers in part on the business dealings that the president-elect’s past and present advisers have had . Mr. Manafort has done business in Ukraine and Russia. Some of his contacts there were under surveillance by the National Security Agency for suspected links to Russia’s Federal Security Service.
Mr. Manafort is among at least three Trump campaign advisers whose possible links to Russia are under scrutiny. Two others are Carter Page, a businessman and former foreign policy adviser to the campaign, and Roger Stone, a longtime Republican operative.
In August, The Times reported that Mr. Manafort’s name had surfaced in a secret ledger that showed he had been paid millions in undisclosed cash payments.
Handwritten ledgers show $12.7 million in undisclosed cash payments designated for Mr. Manafort from Mr. Yanukovych’s pro-Russian political party from 2007 to 2012, according to Ukraine’s newly formed National Anti-Corruption Bureau. Investigators assert that the disbursements were part of an illegal off-the-books system whose recipients also included election officials.
In addition, criminal prosecutors are investigating a group of offshore shell companies that helped members of Mr. Yanukovych’s inner circle finance their lavish lifestyles, including a palatial presidential residence with a private zoo, golf course and tennis court. Among the hundreds of murky transactions these companies engaged in was an $18 million deal to sell Ukrainian cable television assets to a partnership put together by Mr. Manafort and a Russian oligarch, Oleg Deripaska, a close ally of President Vladimir V. Putin.
Mr. Stone, a longtime friend of Mr. Trump’s, said in a speech in Florida last summer that he had communicated with Julian Assange, the founder of WikiLeaks, the anti-secrecy group that published the hacked Democratic emails. During the speech, Mr. Stone predicted further leaks of documents, a prediction that came true within weeks.
In a brief interview , Mr. Stone said he had never visited Russia and had no Russian clients. He said that he had worked in Ukraine for a pro-Western party, but that any assertion that he had ties to Russian intelligence was “nonsense” and “totally false.”
“The whole thing is a canard, I have no Russian influences.”
Investigators are also scrutinizing people on the periphery of Mr. Trump’s campaign, such as Mr. Page, a former Merrill Lynch banker who founded Global Energy Capital, an investment firm in New York that has done business with Russia.
In an interview on Thursday, Mr. Page expressed bewilderment about why he might be under investigation. He blamed a smear campaign — that he said was orchestrated by Mrs. Clinton — for media speculation about the nature of his ties to Russia.
“I did nothing wrong, for the 5,000th time,” he said. His adversaries, he added, are “pulling a page out of the Watergate playbook.”
The lingering investigations will pose a test for Senator Jeff Sessions, Republican of Alabama, who has been nominated for attorney general. If Mr. Sessions is confirmed, he will for a time be the only person in the government authorized to seek foreign intelligence wiretaps on American soil.