Jan 2 (Reuters) - Iberdrola's U.S. unit Avangrid Inc terminated its $8.3 billion deal, including debt, for rival PNM Resources as it could not get all necessary regulatory approvals to close by Dec. 31, the U.S. power utility said in a statement on Tuesday.

The two power utility companies had obtained all necessary approvals except that of the New Mexico Public Regulation Commission, the statement said.

The regulator had rejected Avangrid's proposed acquisition of PNM Resources in 2021, saying the deal's risks outweighed its promised benefits to state ratepayers.

There was no clear timeline for the resolution of a court review for the denial or other subsequent regulatory actions, Avangrid added.

Avangrid reaffirmed its 2023 forecast for earnings per share (EPS) and adjusted EPS, while PNM Resources said it would provide a financial update, including its preliminary results, in February.

The deal, worth $4.3 billion excluding debt, was unanimously approved by PNM's board in 2020 and was expected to create a renewable energy operator with a combined market value topping $20 billion.

"While the PNM Resources Board of Directors approved an extension, it was not accepted by Avangrid and Avangrid terminated the merger," PNM Resources said in a separate statement.

(Reporting by Jyoti Narayan in Bengaluru; Editing by Savio D'Souza and Janane Venkatraman)