US politicians investigating the January 2021 attack on the Capitol have asked the daughter of former president Donald Trump to cooperate voluntarily with its inquiry.
In a letter marking a major step for the investigation inside Mr Trump's inner circle, the House select committee told Ivanka Trump - then a senior advisor to her father - it had evidence that she had pleaded with him to call off the violence as his supporters stormed Congress.
"Testimony obtained by the committee indicates that members of the White House staff requested your assistance on multiple occasions to intervene in an attempt to persuade President Trump to address the ongoing lawlessness and violence on Capitol Hill," chairman Bennie Thompson told her.
Investigators are looking into how the attack, which shut down Congress, took place and whether then-president Mr Trump and members of his circle had a part in encouraging it.
The committee has already issued subpoenas for several key figures in Mr Trump's orbit, including White House chief of staff Mark Meadows and one-time White House strategist Steve Bannon.
The committee said Ivanka Trump's actions as the riot was underway were a "key focus" of the probe, and that she appeared to have direct knowledge of her father's attempt to persuade then-vice president Mike Pence to stop the counting of electoral votes.
"As January 6 approached, President Trump attempted on multiple occasions to persuade vice president Pence to participate in his plan," Mr Thompson wrote.
"One of the president's discussions with the vice president occurred by phone on the morning of January 6. You were present in the Oval Office and observed at least one side of that telephone conversation."
The panel said in a statement it was also seeking information from Ivanka Trump about concerns voiced by White House lawyers, politicians and Pence aides about plans to pressure the vice president to overturn the election.
Ivanka Trump served as an aide to her father. Source: EPA
"The committee would like to discuss any other conversations you may have witnessed or participated in regarding the president's plan to obstruct or impede the counting of electoral votes," Mr Thompson wrote.
The action came after the committee scored a major win in its legal battle for documents related to the attack that were being blocked by the president.
The US Supreme Court on Wednesday rejected Mr Trump's bid to prevent the records held by the National Archives from being given to investigators.
Documents that Mr Trump hoped to block include emails, phone records, briefing materials and other records.
He had also sought to block the release of the White House Daily Diary - a record of his activities, trips, briefings and phone calls.
On Tuesday, the committee issued subpoenas to former New York mayor Rudy Giuliani - a key figure in Mr Trump's failed bid to overturn the election - and three other allies of the defeated ex-president.
Joyce Vance, legal analyst and former US lawyer in Alabama, congratulated the committee for "continuing to play hardball" in its investigation.
"After yesterday's (Supreme Court) ruling, tough to see any way out of complying for Ivanka - even if she takes the 5th, she has to engage," he tweeted.
"There is no daddy/daughter privilege."
