PORTLAND — UNUM Corp. said it has agreed with London-based INVESCO MIM PLC to purchase National Employers Life Assurance Holding Co. Ltd., for some $64 million.

The British company markets life insurance, mortgages and pension products in addition to permanent health insurance, UNUM said Monday in a statement.

The deal is subject to approval by Britain’s Department of Trade and Industry, and the approval of INVESCO MIM’s shareholders might also be required, UNUM said. UNUM spokeswoman Kathryn A. Yates said Monday that corporate officials were not immediately sure whether shareholders will have any input on the sale, which is expected to be completed by June 30.