(CNN) Federal prosecutors in New York have requested interviews in recent weeks with executives at the Trump Organization, according to people familiar with the matter, signaling a growing potential threat to President Donald Trump and those in his orbit from criminal investigations by the Manhattan US Attorney's office.

Trump and his legal team have long harbored concerns that investigations by New York federal prosecutors -- which could last throughout his presidency -- may ultimately pose more danger to him, his family and his allies than the inquiry by special counsel Robert Mueller, according to people close to Trump. Prosecutors' recent interest in executives at Trump's family company may intensify those fears.

The specific inquiry or topics of interest by prosecutors in any interviews with Trump Organization executives wasn't immediately clear. The sources were not authorized to speak on the record. A spokesperson for the company didn't respond to a request for comment.

New York federal prosecutors in recent months have undertaken at least two investigations into Trump-related entities. The first one, which CNN has reported stemmed from the office's case against Trump's former personal attorney, Michael Cohen, is examining possible campaign-finance violations by executives at the Trump Organization during the company's effort to reimburse Cohen for hush-money payments he made or orchestrated to silence women who claimed affairs with Trump. Trump has denied those affairs.

In the Cohen probe, one Trump Organization executive, chief financial officer Allen Weisselberg, was granted immunity by federal prosecutors to provide information concerning Cohen, CNN has reported.

The second investigation concerns the Trump inaugural committee and possible financial abuses related to the more than $100 million in donations raised for his inauguration, CNN has reported.

On Monday, prosecutors issued a sweeping subpoena to the committee, requesting documents related to virtually every donor or donation, attendee at a committee event, piece of paperwork related to the legal requirements attached to donations and even "the possibility of" donations made by foreign nationals.

The subpoena, a copy of which was reviewed by CNN, also disclosed that prosecutors are investigating an array of potential crimes, including conspiracy against the US, false statements, mail fraud, wire fraud, money laundering, inaugural committee disclosure violations, and violations of laws prohibiting contributions by foreign nations and contributions in the name of another person, also known as straw donors.

A spokeswoman for the committee said Monday that it would cooperate with the inquiry. Trump's attorney Rudy Giuliani said Tuesday that Trump "had little to no involvement in the inaugural committee."

While prosecutors in New York haven't charged any Trump-linked officials aside from Cohen, who pleaded guilty in August and is set to begin his prison sentence in March, they have undertaken various investigative steps in addition to the subpoena.

Prosecutors have questioned at least two former Trump campaign officials, according to people familiar with the matter. One official who was questioned last summer was asked about coordination between the Trump Organization and the campaign, one of these people said.

Investigators asked this official how the Trump Organization was structured and which accounts were used to pay campaign staffers and other campaign-related bills, this person said.

Despite the flurry of recent activity from the Manhattan US Attorney's office, however, it's not clear that any of its ongoing inquiries will result in charges. The investigation into possible campaign-finance violations at the company appears to be in its final stages, according to one person involved in it.