LONDON, Nov 17 (Reuters) - Spanish energy company Iberdrola plans to make a bid for Electricity North West (ENWL) that could value the British power distribution network at up to 3.5 billion pounds ($4.34 billion), according to two sources familiar with the matter.

The sources told Reuters in October that ENWL shareholders are working with investment bank Jefferies on a strategic review of the grid operator, which supplies electricity to some five million customers in Manchester, Lancashire and Cumbria.

Iberdrola declined to comment on any involvement in the ENWL sale process, which one of the sources who spoke on condition of anonymity said is expected to begin in December.

ENWL is owned by a consortium led by Japan's Kansai Electric Power Co (Kepco) and investment fund Equitix, both of which hold a 40% stake, according to the company's annual report.

Macquarie and KKR may also consider bids for ENWL, according to one of the people cited and a third with knowledge of the sale process, who added that discussions are at an early stage and there is no certainty that they will lead to a deal.

Spokesmen for Macquarie, KKR, Equitix and Kansai Electric declined to comment.

The ENWL purchase could help Iberdrola connect areas it already serves through its Scottish Power business. This supplies power to 3.6 million customers in Merseyside, Cheshire, north Wales and north Shropshire in England, and central and southern Scotland, according to its latest annual report.

The Spanish group was considering a bid for ENWL in 2019, when its then-owners JP Morgan and Colonial First State launched a sale that was eventually won by existing shareholders.

Iberdrola is accelerating its investments in power grids, aiming to deploy €27 billion by 2025, with the goal of achieving 30% growth in operating profit from its grids unit to €8.5 billion.

This figure is equivalent to 57% of Iberdrola's total planned investments between 2023 and 2025, which will be partially financed by asset sales.

Iberdrola expects to receive about €6 billion from alliances and asset sales by the end of the year that will help it close 2023 with net debt of about €43 billion, roughly in line with 2022.

(1 U.S. dollar = 0.8067 pounds)

(Reporting by Andres Gonzalez; additional reporting by Pietro Lombardi; editing by Anousha Sakoui and Alexander Smith; Spanish editing by Javi West Larrañaga)