A watchdog group on Tuesday called for the Securities and Exchange Commission and the Senate Select Committee on Ethics to launch an investigation into millions of dollars worth of stock trades made since 2008 by Sen. Bob Corker and members of his family. InsideSources has also uncovered a letter from Corker’s accountant to the Ethics Committee that appears to contradict the explanation being offered for revisions that have been made to the Tennessee Republican’s financial disclosure forms.

In a release that follows a Wall Street Journal report on the trades last week, the nonprofit Campaign for Accountability says Corker, who chairs the Senate Foreign Relations Committee and is a senior Banking Committee member, made 70 trades of stock in Chattanooga-based real estate investment giant CBL & Associates Properties, and that some of those trades “closely preceded company announcements that led to changes in the stock’s price and seemingly resulted in the senator making millions of dollars.”

According to the WSJ, after the newspaper asked about “apparent discrepancies” in his financial disclosures, the senator amended his documents to reflect the CBL stock purchases.

A spokesperson in the senator’s office on Tuesday blamed any errors on the disclosure forms on Corker’s accountants: “These baseless ‎accusations from a political special interest group are categorically false and nothing more than a smear campaign. The senator always has disclosed to the public that he invests in CBL since he first held stock in the company back in 2007. The accounting firm that worked on his financial disclosure reports properly listed the sale and gain or loss of transactions, but some did not list the day they were purchased, so after completing a full review, we are correcting this technical oversight.”

While Corker’s office has placed blame on the accounting firm, a 2013 letter sent to the Ethics Committee by Corker’s accountant, David DiStefano, places blame on Corker’s brokerage firm, UBS, for failure to provide details about Corker’s trades.

The second-term senator ranks No. 23 on CQ Roll Call’s list of wealthiest members of Congress, with an estimated minimum net worth of at least $17.98 million.

The Campaign for Accountability reports Corker recently amended his filings to disclose a 2009 purchase of between $1 and $5 million of CBL stock, sold just five months later in 2010 at a 42 percent profit.

Subsequent stock purchases also brought Corker large gains, according to the watchdog group, which formed earlier this year and is headed by longtime Citizens for Responsibility and Ethics in Washington counsel Anne Weismann.

The group describes itself as an “organization that uses research, litigation, and aggressive communications to expose misconduct and malfeasance in public life and hold those who act at the expense of the public good accountable for their actions.”