The Securities and Exchange Commission staff charged a former board member of Goldman Sachs with insider trading Tuesday, saying he leaked sensitive information about the investment powerhouse to hedge fund billionaire Raj Rajaratnam.

Rajat K. Gupta was also charged with tipping off Rajaratnam about earnings at Procter & Gamble, where Gupta resigned Tuesday as a member of the board.

The charges are part of an expanding probe of insider trading that has led to a string of SEC enforcement actions and criminal charges against lawyers, consultants, accountants, corporate insiders and hedge fund managers.

Gupta moved in the highest echelons of the business world, and served for years as head of the international consulting firm McKinsey & Co.

Rajaratnam, who founded Galleon Management, has been a major focus of the investigations and is awaiting trial on charges of securities fraud and conspiracy. He and Galleon parlayed Gupta’s tips into more than $18 million of investment gains or averted losses, the SEC staff alleges.

An attorney for Gupta, Gary Naftalis, said the SEC staff allegations “are totally baseless.”

“Mr. Gupta’s 40-year record of ethical conduct, integrity, and commitment to guarding his clients’ confidences is beyond reproach,” Naftalis said in a statement. “Mr. Gupta has done nothing wrong and is confident that these unfounded allegations will be rejected by any fair and impartial fact finder.”

Rajaratnam is fighting the government’s charges, and a Web site devoted to his defense says he “intends to establish his innocence at trial before a jury of his fellow citizens.”

Immediately after Goldman Sachs directors met by phone in September 2008, at the height of the financial crisis, and approved a $5 billion infusion by Warren Buffett’s Berkshire Hathaway, Gupta phoned Rajaratnam, the SEC staff said. Less than a minute after Gupta’s call, Rajaratnam arranged for Galleon funds to buy Goldman shares, the SEC staff said.

The next day, after the Berkshire investment was announced, Galleon sold the Goldman shares at a profit, the SEC staff said.

Gupta, 62, was educated at the Indian Institute of Technology and Harvard Business School. He was a business associate of Rajaratnam, and at the time of the alleged insider trading, he had at least an indirect financial stake in Galleon hedge funds, the SEC staff said.

“Gupta was honored with the highest trust of leading public companies, and he betrayed that trust by disclosing their most sensitive and valuable secrets,” Robert Khuzami, the SEC’s enforcement director, said in a news release.

Goldman Sachs announced last year that Gupta would not seek reelection to its board, before he was publicly linked to the insider trading probe. A Goldman Sachs spokesman declined to comment Tuesday.

Procter & Gamble, a major consumer products company, said Gupta resigned from its board Tuesday “in the interests of the Company to prevent any distraction.” The company said it was cooperating with the government.

Gupta remains on the board of AMR Corp., parent of American Airlines, and he is listed as a director at Harman, a maker of audio equipment.

Another former senior partner at McKinsey, Anil Kumar, pleaded guilty to conspiracy and securities fraud charges in the Galleon probe last year. He was accused of conveying inside information to Rajaratnam about McKinsey clients such as a subsidiary of eBay, and the government alleged that he arranged to have an “overseas entity” receive payments from Rajaratnam through a Swiss bank account.

Commenting on the case against Gupta, McKinsey spokeswoman Yolande Daeninck said the firm was saddened to learn about it.

The administrative charges against Gupta could lead to financial penalties, a requirement that he give up ill-gotten gains, and an order barring him from serving as an officer or director of a public company.

On the night of June 10, 2008, after Goldman chief executive Lloyd Blankfein briefed Gupta on an upcoming earnings report, “a flurry of short calls” ensued between Gupta and Rajaratnam, the SEC staff said. The next morning, Galleon began trading on the information, and the illicit profits exceeded $13.6 million, the SEC staff said.

As a member of the audit committee at Procter & Gamble, Gupta dialed into a committee conference call in January 2009 covering a planned earnings release. The same day, he called Rajaratnam, and Galleon began short-selling Procter & Gamble shares, betting, in effect, that the stock price would fall, the SEC staff said.

The bet paid off, generating more than $570,000 of illicit profits, the SEC staff said.

“There is no allegation that Mr. Gupta traded in any of these securities or shared in any profits as part of any quid pro quo,” Gupta’s attorney said. “In fact, Mr. Gupta had lost his entire $10 million investment in the GB Voyager Fund managed by Rajaratnam at the time of these events, negating any motive to deviate from a lifetime of honesty and integrity.”