An ethics watchdog has filed a complaint against Rep. Devin Nunes (R-Calif.), alleging that the lawmaker failed to fully disclose investments in three California companies.

The nonpartisan Campaign for Accountability says Nunes failed to disclose income from a 2006 investment in Alpha & Omega Winery until 2013, despite the winery's "apparent success."

The complaint also states that Nunes had invested in Alpha & Omega's sister winery, Phase 2 Cellars, in 2015. Nunes's investment reportedly amounted to between $50,001 and $100,000, despite the winery requiring that shareholders make a minimum investment of $200,000.

The group claims that Nunes "may have accepted an improper gift in violation of House rules" if he was allowed to invest less than other investors.

"If, however, Rep. Nunes actually invested $200,000 in Phase 2, then it appears he may have willfully violated disclosure rules as on his [personal financial disclosure reports] PFDs for 2015, 2016, and 2017," the group states.

The watchdog also says Nunes never listed ownership of or investment in Vidonia LLC, a financial holding company that operated between 2006 and 2009, despite a 2007 Securities and Exchange Commission filing naming Nunes and his wife as beneficial owners.

The group is requesting that the Office of Congressional Ethics launch a probe into whether Nunes violated any ethics rules by failing to disclose the alleged investments.

"It's amusing to see The Hill reprint a press release by a left-wing group whose sole function seems to be filing frivolous ethics complaints against Republicans," a spokesman for Nunes told The Hill.

"While unethical conduct by any member of Congress is problematic, it's even worse for the chair of the House Intelligence Committee, who conducts investigations in which witnesses are expected to testify truthfully and can be prosecuted for failing to do so," Campaign for Accountability Executive Director Daniel Stevens said in a statement.

"What's good for the goose is good for the gander. If he lied on his PFDs, Rep. Nunes should be held accountable," Stevens continued.

Nunes is the GOP chairman of the House Intelligence Committee and led the committee's investigation into Russian interference in the 2016 presidential election.