FRANKFURT, Nov 10 (Reuters) - Germany has acquired a minority stake in local utility EnBW's high-voltage business, the company said on Friday, firming up its grip on critical energy infrastructure in a bid to speed up the country's energy transition.

The purchase of a 24.95% stake in EnBW's TransnetBW by state lender KfW has been long in the making and increases the government's exposure in the sector, which already includes a 20% stake in rival network 50Hertz.

EnBW earlier this year already sold a 24.95% stake in TransnetBW to a savings banks-led consortium for around 1 billion euros ($1.1 billion).

The group confirmed that KfW had bought its stake at the same conditions, without providing details. KfW declined to comment when asked about the purchase price.

"We are delighted to welcome two long-term oriented and reliable co-investors on board at TransnetBW," EnBW finance chief Thomas Kusterer said in a statement.

"This provides EnBW with additional funding for growth investments to accelerate the implementation of the energy transition in Germany."

To further increase ownership of the power transmission sector, which is considered key to Germany's energy security, Berlin is also trying to purchase the German division of Dutch operator TenneT for more than 20 billion euros.

($1 = 0.9366 euros) (Reporting by Christoph Steitz; Editing by Jan Harvey)