As Robert Mueller’s investigation continues, federal prosecutors in New York have separately ordered Donald Trump’s inaugural committee to turn over documents related to the $107m celebration marking the start of his presidency in 2017.

Inaugural committee spokeswoman Kristin Celauro told the Associated Press that the committee had received the subpoena and was still reviewing it. “It is our intention to cooperate with the inquiry,” she said.

A second spokesman, Owen Blicksilver, declined to answer questions about which documents prosecutors requested. The US attorney’s office in Manhattan, which issued the subpoena, declined to comment.

The investigation is yet another legal threat surrounding the president as he prepares for the State of the Union address on Tuesday. The Russia inquiry, which has ensnared several senior figures from his presidential campaign, appears close to the end. But the administration is preparing for a blitz of oversight investigations that the newly empowered House Democrats have promised.

The subpoena, first reported by ABC, represents an escalation of the investigation, headed by the public corruption unit of the Manhattan US attorney’s office.

The New York Times and the Wall Street Journal, citing sources familiar with the investigation, reported that federal prosecutors in New York’s southern district on Monday issued a subpoena related to the committee’s donors, finances and activities. Prosecutors are also examining whether any foreigners made illegal payments to the committee, the newspapers reported.

US investigates whether Trump's inaugural cash was spent improperly – report Read more

﻿No one working for the committee has been accused of wrongdoing, the reports said, and there is no indication that the matter relates directly to Trump.

The Wall Street Journal reported in December that prosecutors were in the “early stages” of an investigation into whether Trump’s inaugural committee and a pro-Trump Super Pac received illegal donations from foreigners hoping for influence over US policy.

Investigators are reportedly examining how the committee spent the money as well as whether the donations – a record sum raised for such an event – were made in return for influence over policy or access to the Trump administration as it entered power.

The Times reported that the inquiry was focused on whether individuals from Qatar, Saudi Arabia and other Middle Eastern nations used “straw donors” to hide their own gifts to the Trump funds.

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The Journal reported that the investigation arose from an FBI raid on the home of Michael Cohen, Donald Trump’s longtime lawyer and fixer who has been sentenced to three years in prison for lying to Congress and facilitating illegal payments to silence two women who alleged affairs with Trump.

FBI agents raided Cohen’s home and office in April, which resulted in the disclosure of a recorded conversation between the lawyer and Stephanie Winston Wolkoff, a former adviser to Melania Trump, according to the newspaper. In the conversation, Wolkoff, one of the main producers of the 20 January 2017 inauguration celebrations, is alleged to have “expressed concern” about how the inaugural committee was spending the money it had raised.