The FBI is looking into alleged insider trading in the options of ketchup maker H.J. Heinz Co before its blockbuster acquisition last week by Warren Buffett and Brazil's 3G Capital, a bureau spokesman said on Tuesday.

Buffett's Berkshire Hathaway and 3G said last Thursday they would buy Heinz for $23 billion in cash. Almost immediately, options market players noted extremely unusual activity the day before the deal.

On Friday, the U.S. Securities and Exchange Commission filed a suit against unknown traders who it said used a Goldman Sachs account in Switzerland to trade on purported inside knowledge of the transaction.

On Tuesday, the Federal Bureau of Investigation said it was joining in as well.

"The FBI is aware of the trading anomalies the day before Heinz' announcement," a spokesman said. "The FBI is consulting with the SEC to determine if a crime was committed."

A spokeswoman for the investor group declined to comment on the FBI's involvement. A spokesman for Goldman Sachs said the bank is cooperating with authorities' investigations.

(Reporting By Emily Flitter; Additional reporting by Ben Berkowitz in Boston and Dan Wilchins in New York; Editing by Gary Hill and Jim Marshall)