(CNN) Commerce Secretary Wilbur Ross on Thursday admitted to "errors" in failing to divest assets required by his government ethics agreement and said he would sell all his stock holdings.

The admission comes after Washington's chief ethics watchdog took Ross to task for what it said were inconsistencies in his financial disclosure forms.

Ross' failure to divest certain investments "created the potential for a serious criminal violation," the Office of Government Ethics (OGE) said in a letter outlining various omissions and inaccurate statements in disclosure and compliance documents Ross filed with the agency.

In a statement late Thursday, Ross acknowledged "inadvertent errors."

"My investments were complex and included hundreds of items," he said. "I self-reported each error, and worked diligently with my department's ethics officials to make sure I avoided any conflicts of interest."

David Apol, the acting director and general counsel of the OGE, said in the letter that the agency had "no information to contradict" Ross' assertion that the omissions and inaccuracies were inadvertent.

According to the letter, Ross signed an ethics agreement in November 2017 saying he had completed divestitures that he agreed to earlier in the year.

But the following month, he submitted a report saying he had sold stock in his former company Invesco on December 19 and 20. That was "well after the date of your compliance document and the date by which you agreed to divest this asset," Apol wrote.

The letter said Ross also breached the agreement by opening new short positions -- bets that a stock price will fall -- on holdings that he had previously committed to sell. He did so without asking for advice beforehand from ethics staff members, it added.

The short bets "appear to have been an ineffective attempt to remedy your actual or apparent failure to timely divest assets per your Ethics Agreement," Apol wrote.

"Even inadvertent errors regarding compliance with your ethical obligations can undermine public trust in both you and the overall ethics program," the letter said. "Furthermore, your actions, including your continued ownership of assets required to be divested in your Ethics Agreement and your opening of short sale positions, could have placed you in a position to run afoul of the primary criminal conflict of interest law."

In his statement, Ross said he takes his "ethics obligations very seriously" and is "committed to serving the American people."

He said he has directed all his equity holdings to be sold and proceeds placed in US Treasury securities.

- Kevin Bohn contributed to this report.