CANTON, Mass.—OneBeacon Insurance Group Ltd. said Friday that it has sold renewal rights to its nonspecialty commercial lines insurance unit to Hanover Insurance Group Inc.

The deal includes small commercial accounts and the nonspecialty portion of Canton, Mass.-based OneBeacon’s middle-market business, beginning with Jan. 1, 2010, renewal dates.

OneBeacon will receive $23.25 million plus 10% for premiums renewed above $200 million as consideration from Worcester, Mass.-based Hanover, OneBeacon said in a statement.

Direct premiums total approximately $490 million for the book of business that has been sold, OneBeacon said.

OneBeacon’s specialty and personal lines will not be affected, and it will keep its technology, financial services, excess property and property inland marine commercial segments, the insurer said.

Capital freed from the competitive commercial market will allow greater flexibility and growing its specialty business, OneBeacon said.