Ltd. (OPL), has abruptly resigned, effective yesterday.

An announcement gave no details of his departure. But the long-serving executive has indicated he will be available as a consultant from his new home in the United States.

No immediate replacement was named, suggesting that the company was caught off guard by the decision.

Vice president and secretary Thomas E. Butler said that the company board of directors was "actively searching'' for a replacement.

"We're sorry to see him go,'' Mr. Butler said. "And we wish him the best.'' The well-respected and well-liked Mr. Barone has been involved with OPL since its incorporation in 1983.

He became CEO in December 1995 after an earlier career as a financial executive at UPS. He previously served as OPL's chief operating officer.

OPL is one of the largest multi-line reinsurance companies.