Escalating one of the investigations into President Trump’s inaugural committee, federal prosecutors ordered on Monday that its officials turn over documents about donors, finances and activities, according to two people familiar with the inquiry.

The subpoena seeks documents related to all of the committee’s donors and guests; any benefits handed out, including tickets and photo opportunities with the president; federal disclosure filings; vendors; contracts; and more, one of the people said.

The new requests expand an investigation prosecutors opened late last year amid a flurry of scrutiny of the inaugural committee. And they showed that the investigations surrounding Mr. Trump, once centered on potential ties to Russia during the 2016 presidential election, have spread far beyond the special counsel’s office to include virtually all aspects of his adult life: his business, his campaign, his inauguration and his presidency.

In the subpoena, investigators also showed interest in whether any foreigners illegally donated to the committee, as well as whether committee staff members knew that such donations were illegal, asking for documents laying out legal requirements for donations. Federal law prohibits foreign contributions to federal campaigns, political action committees and inaugural funds.

A spokesman for the inaugural committee said it was still reviewing the subpoena and intended to cooperate with the investigation. A spokesman for the United States attorney’s office in Manhattan declined to comment. ABC first reported that a subpoena was in the works.

Prosecutors have pursued the possibility that the inaugural committee made false statements to the Federal Election Commission, according to people familiar with the matter. It can be a crime to knowingly make false or fraudulent statements to a federal agency.

The inaugural committee disclosed a list of its donors to the commission, and the prosecutors are examining whether that list is complete and accurate, the person said. If a donor was omitted from the report, prosecutors could take an interest in that, as well.

The inaugural committee’s chairman was Thomas J. Barrack, a close friend of the president’s. Mr. Barrack’s close aide working on the committee was Rick Gates, the former deputy to Paul Manafort, the former Trump campaign chairman who has been convicted of and pleaded guilty to several crimes in connection with the investigation by the special counsel, Robert S. Mueller III. Mr. Gates has pleaded guilty to financial fraud and lying to the F.B.I., and has been cooperating with Mr. Mueller’s team for nearly a year.

No one who worked for the committee has been accused of wrongdoing, and a subpoena is an initial step in the inquiry. Mr. Barrack and other inaugural committee officials are not named in it.

The United States attorney’s office in Brooklyn is separately investigating whether inaugural officials helped foreigners illegally funnel donations to Mr. Trump’s inaugural committee using so-called straw donors to disguise their donations, people briefed on that inquiry said.

As part of their own inquiry, the prosecutors in Manhattan are questioning whether foreign nationals illegally donated to Mr. Trump’s inaugural committee.