EXEL Ltd. will not increase its share holdings in property catastrophe reinsurer Mid Ocean Ltd. above existing levels, according to a release from Mid Ocean.

EXEL has confirmed to Mid Ocean, subject to certain conditions, it will not, without Mid Ocean directors' consent, increase its ownership of Mid Ocean shares above 30 percent of Mid Ocean's outstanding voting shares or more than 25 percent of Mid Ocean's shares on a fully diluted basis, said Mid Ocean.

The arrangement is in place until May 1998.

EXEL was a founding shareholder of Mid Ocean and owns about 30 percent of Mid Ocean's outstanding voting shares and about 25 percent of Mid Ocean's shares on a fully diluted basis.

EXEL, through its wholly-owned subsidiaries X.L. Insurance company, Ltd. and X.L. Europe, provides general liability, directors and officers liability and professional liability insurance coverage.

In connection with the previously announced authorisation by directors of Mid Ocean for the repurchase of up to $75 million of Mid Ocean shares, EXEL has confirmed its intention to decrease proportionally the number of shares of Mid Ocean owned by it so as to maintain its percentage ownership of Mid Ocean at a level no greater than present, Mid Ocean said.

Mid Ocean Limited Inc. also announced Friday the election of Sir Brian Corby and Mr. Michael Esposito Jr. to its board of directors.

Sir Brian Corby was formerly chairman and CEO of Prudential Corp. plc. He joined Prudential Assurance Company Ltd. in 1952 and became chief executive of the Prudential Corp., the holding company of the Prudential group, in 1982 and chairman in 1990, a position he has recently retired from after completing a five year term.

He has also served as president of the Confederation of British Industry, president of the Geneva Association and director of the Bank of England.

Mr. Esposito is presently chairman of the Board of EXEL.

He is executive vice president of the Chase Manhattan Corp., from which he will retire June 30.

Until 1994, Mr. Michael Kevany, Mr. Esposito's predecessor as chairman of EXEL, was a member of the board and executive committee of Mid Ocean.

"We are very pleased to have two individuals with such vast experience join Mid Ocean's board. They are sure to make many valuable contributions to the board,'' said Mid Ocean president and CEO Mr. Michael Butt.

The company also on Friday declared a regular quarterly cash dividend of 25 cents per share.

The dividend applies to the company's common stock and is payable July 11 to shareholders of record June 23.

Mid Ocean, through its wholly-owned subsidiary Mid Ocean Reinsurance Company Ltd., provides property catastrophe and other reinsurance to insurers and reinsurers.