Adds context, details

By Benoit Van Overstraeten

AMSTERDAM, June 30 (Reuters) - The Netherlands will announce in September whether it will sell a minority stake in the German arm of power grid operator TenneT or pursue a partial IPO, the government said on Monday, in what could be one of Europe's biggest deals in 2025.

The Dutch government embarked on a dual track process for TenneT Germany after a partial sale to German state lender KfW KFW.UL failed to materialise last June. It had initially hoped to come to a decision before the summer break.

"Based on the information I have received in recent weeks, I note that many investors are interested in participating in TenneT Germany," Dutch finance minister Eelco Heinen said in a letter to the president of the lower house of parliament.

TenneT Germany had a regulated asset base, a key valuation gauge for energy grids, of 27.8 billion euros ($31 billion) as of 2024, which is set to increase by 25% each year through 2029, according to an investor presentation on its website.

"Originally, the decision moment between the IPO and the private issue was scheduled around the start of the summer recess," Heinen said.

"Both pathways could be promising and attractive options to meet the capital needs. I have therefore decided to elaborate both pathways in parallel this summer (...) I intend to let you know in September which of the two options will be implemented."

Heinen also said that several investors had made non-binding offers for a minority stake in TenneT Germany.

Last month, Reuters cited sources as saying that funds including Apollo Global Management APO.N, Canada's Caisse de depot et placement du Quebec and Macquarie MQG.AX were interested in such a sale, and that BlackRock-owned BLK.N Global Infrastructure Partners and CPP Investment Board, which manages Canadians' pension savings, might be too.

The sources added that a sale of new shares in TenneT Germany could raise up to 12 billion euros ($14 billion), although they said the amount could be significantly lower depending on the size of the stake sold and the level of debt.

In his letter, Heinen said that any partial IPO IPO-TTH.AS of TenneT Germany would occur in the fourth quarter of 2025.

($1 = 0.8498 euros)

(Additional reporting by Bart Meijer. Editing by Susan Fenton and Mark Potter)

((benoit.vanoverstraeten@thomsonreuters.com; +33149495339;))