Goldman Sachs Group Inc. (GS), the fifth- biggest U.S. bank by assets, raised estimates of potential losses from legal claims by 13 percent and said a probe into its handling of Greek finances includes trading and research.

The forecast of “reasonably possible” legal costs rose to $2.7 billion as of March 31 from $2.4 billion three months earlier, according to a regulatory filing today. The New York- based firm didn’t give specific reasons for the increase.

Banks started releasing estimates of possible losses after the U.S. Securities and Exchange Commission told finance chiefs in October 2010 that they should disclose such costs “when there is at least a reasonable possibility” they may be incurred, even if the risk is too low to require reserves.

The estimate doesn’t include potential losses from legal matters that are at an early stage or where the firm can’t determine the potential amount, according to the filing.

An investigation of the firm’s financing and swap transactions with the Greek government, which started about two years ago, also includes “trading and research activities with respect to Greek sovereign debt,” according to today’s filing. “Goldman Sachs has cooperated with the investigations and reviews,” the company said.

[Bloomberg]