Hunter Biden on Wednesday sued Overstock.com’s former chief executive Patrick Byrne alleging defamation over comments he made about seeking a bribe from Iran.

According to the lawsuit, Byrne published false statements in June claiming that the president’s son reached out to the Iranian government in 2021, offering to have his father “unfreeze” $8 billion in Iranian funds for a bribe.

“These defamatory statements by Byrne are not merely false and not merely malicious—they are completely outrageous,” Biden’s attorneys wrote in the lawsuit, filed in federal court in California.

Byrne, a staunch Trump ally, reposted the “false and defamatory” statements alleging Biden had corrupt and treasonous dealings with Iran on X on Oct. 8, the lawsuit says, a day after Hamas attacks in Israel killed about 1,400 people.

Biden’s attorneys said the post implied his “allegedly criminal and corrupt actions had contributed to the terrorist attacks by Hamas.”

“Byrne knows his statements are baseless and yet published and republished them anyway, and he continues to propagate his lies to anyone who will listen, including his hundreds of thousands of social media followers,” they added.

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Biden’s attorneys also said that they sent a formal demand for retraction to Byrne on Oct. 26 but that he has “ignored” the demand and “has taken no steps to disavow his false claims.”

An attorney for Byrne was not listed in Wednesday’s court filing. A lawyer representing Byrne in separate pending lawsuits did not immediately respond to a request for comment Wednesday night.

Biden filed the lawsuit the same day House Republicans subpoenaed him and the president’s brother James Biden.

Byrne, who has also been sued for defamation by Dominion Voting Systems, promoted former President Donald Trump’s false election claims in the aftermath of the 2020 contest. He was also present at an Oval Office meeting on Dec. 18, 2020, when a group of Trump allies urged the then-president to invoke a national emergency to stay in office, former White House counsel Pat Cipollone testified last year.

Wednesday’s lawsuit is the latest in a string of suits Biden has filed in recent months as House Republicans step up probes of the president and his family in an impeachment inquiry.

In a pair of lawsuits in September, Biden alleged that two IRS agents were unlawfully sharing his tax information, and he alleged data access violations and computer fraud by Rudy Giuliani, his businesses and his former lawyer Robert Costello.