* Traders remain unidentified
* Swiss authorities assisting SEC
* Account frozen pending further proceedings
By Bernard Vaughan and Katharina Bart and Oliver Hirt
NEW YORK, Feb 22 (Reuters) - A U.S. judge has extended a freeze on a Swiss account linked to possible insider trading in H.J. Heinz Co call options just before the ketchup maker agreed to be bought by Warren Buffett's Berkshire Hathaway Inc and Brazilian investment firm 3G Capital.
The U.S. Securities and Exchange Commission had last Friday won a temporary freeze of the account at Goldman Sachs & Co, one day after Berkshire and 3G announced a $23 billion takeover of Heinz.
U.S. District Judge Jed Rakoff in Manhattan had ordered the temporary freeze, and at a hearing on Friday called the SEC request to extend the freeze "very well warranted."
Rakoff had ordered the trader or traders behind the suspicious trades, who have not been publicly identified, to attend Friday's hearing, but unsurprisingly none showed up.
"They can hide but their assets can't run," Rakoff said.
SEC lawyer Charles Riely told the judge he had no further details on who made the trades.
The FBI and SEC are investigating unusual activity in Heinz call options just ahead of the merger, which the SEC has said resulted in $1.7 million of unrealized profit in the Swiss account, held by a Goldman private wealth client.
These probes recall similar investigations in the middle of the last decade, when a surge in trading activity often preceded announcements of huge buyouts.
Swiss authorities on Friday said they will aid U.S. investigators examining the trades, which options markets participants had noticed almost immediately after the Heinz takeover was announced.
"We're in touch with the SEC and will, as in all cases of this nature, cooperate to the extent of our legal possibilities," Swiss financial regulator FINMA said in a statement on Friday.
Call options allow a buyer to purchase a company's shares at a fixed price in the future, and are a bet that a company's stock price will rise.
Roland Leithaeuser, a Frankfurt-based spokesman for Goldman, said the investment bank is cooperating fully with the SEC. Goldman has not been accused of wrongdoing.
Heinz, Berkshire and 3G have all declined to comment.
The Brazilian founder of 3G, Jorge Paulo Lemann, has made a home in Switzerland since the 1990s. He has not been implicated in wrongdoing over Heinz.
The case is SEC v. Certain Unknown Traders in the Securities of H.J. Heinz Co, U.S. District Court, Southern District of New York, No. 13-01080.