WASHINGTON, Jan 20 (Reuters) - The U.S. House of Representatives" panel investigating the deadly Jan. 6, 2021, attack on the U.S. Capitol on Thursday requested an interview with former U.S. President Donald Trump"s daughter and White House aide Ivanka Trump. In a letter to Ivanka Trump, lawmakers said they were seeking her voluntary cooperation as part of their ongoing probe and would limit their questions to issues related to events surrounding that day, including activities leading up to or influencing it and her role in the White House at that time. The panel noted that she "was present in the Oval Office" during key conversations leading up to Jan. 6, and observed a telephone conversation between her father and former Vice President Mike Pence on the morning of the Capitol attack. Donald Trump had attempted to persuade Pence to reject the results of the election. A statement released by Ivanka Trump"s spokesperson did not address whether she would cooperate with the committee"s investigation. "Ivanka Trump just learned that the January 6 Committee issued a public letter asking her to appear," a spokesperson for Ivanka Trump said in a statement. "As the Committee already knows, Ivanka did not speak at the January 6 rally. As she publicly stated that day at 3:15 p.m., "any security breach or disrespect to our law enforcement is unacceptable. The violence must stop immediately. Please be peaceful."" The committee said in its letter to Ivanka Trump that it also probing whether Donald Trump"s own White House lawyers determined that he broke the law by attempting to interfere with the election outcome. “The committee has information suggesting that President Trump’s White House counsel may have concluded that the actions President Trump directed Vice President Pence to take would violate the Constitution or would be otherwise illegal,” Representative Bennie Thompson, the committee"s chairman, wrote in the letter to Ivanka Trump. The committee said it also wanted to ask whether her father made any effort to deploy federal agents or troops to end the Jan. 6 violence, saying it so far has no evidence of that. The former president has blasted the committee"s probe as a partisan effort, and has sought to block other aides" testimony and White House documents from reaching the panel. U.S. Representative Liz Cheney, vice chair of the committee and one of its two Republican members, said earlier this month that the panel has "firsthand testimony" that Ivanka Trump asked her father to intervene during the Capitol riots. "We know his daughter -- we have firsthand testimony that his daughter Ivanka went in at least twice to ask him to "please stop this violence,"" Cheney said in a Jan. 2 interview with ABC News"s "This Week." Cheney last month shared text messages sent by Donald Trump Jr. pleading with then-White House Chief of Staff Mark Meadows to have the former president urge an end to the Capitol assault. “He’s got to condemn this shit ASAP,” Cheney read aloud from a text sent by Trump Jr., the former president"s eldest son, to Meadows. CNN reported on Tuesday that the committee has subpoenaed and obtained records of phone numbers associated with one of Trump"s children, Eric Trump, as well as Kimberly Guilfoyle, who is engaged to Donald Trump Jr. The committee has spoken to about 400 witnesses and has issued dozens of subpoenas to compel testimony.