Spanish electricity company Iberdrola SA (IBE.MC) Tuesday said it has agreed to sell three U.S. gas units to help finance a major electricity infrastructure project in New England .

Iberdrola has agreed to sell its Connecticut Natural Gas, Southern Connecticut Gas, and Berkshire Gas Company subsidiaries to UIL Holdings Corp. (UIL) in a transaction valued at $1.3 billion.

The sale will finance most of a major infrastructure project in
Maine consisting of the construction and upgrading of approximately 500 miles of transmission lines and five new substations.

The project has an estimated initial investment of $1.4 billion, and will benefit electricity distribution in
Massachusetts , New Hampshire and Maine , as well as the interconnection between Maine and Canada .