(This March 26 story has been corrected to say that the deal will be funded by SEFE, not additional state aid, in paragraph 2)
By Christoph Steitz
FRANKFURT (Reuters) - German nationalised energy company SEFE will take full ownership of gas transmission network WIGA by buying out joint venture partner Wintershall Dea in the latest sign of Berlin tightening its grip on energy infrastructure.
The deal, through which SEFE will acquire the 50.2% stake it does not already own in WIGA, is being funded by the company, it said, after Germany asked Brussels to lift an acquisition ban imposed as part of the group's bailout in 2022.
The transaction still needs to be approved by the EU Commission, SEFE said.
The parties have agreed not to disclose the purchase price for the stake in WIGA, which operates 4,150 km (2,578 miles) of gas grids that link Europe's top economy to five neighbouring states.
Wintershall Dea has said that WIGA's net regulated asset base - a valuation measure for energy grids - was about 3 billion euros ($3.3 billion).
"SEFE being the sole shareholder of WIGA would ensure that (gas pipeline operator) GASCADE can convert the existing high-performance infrastructure to hydrogen in the future," SEFE Chief Executive Egbert Laege said in a statement.
"Transportation infrastructure is a pivotal part of the future hydrogen value chain."
WIGA is a holding company for onshore pipelines Opal, Eugal and NEL, which are connected to the former arrival points of Russian gas via the Nord Stream 1 pipeline - defunct since an explosion in 2022 - at Lubmin on the German Baltic Sea.
The planned deal, which is expected to close by summer, comes as Germany increases its control over energy assets to safeguard national security after Russia's invasion of Ukraine.
Like larger rival Uniper, SEFE, formerly Gazprom (MCX:GAZP) Germania, was rescued by Berlin during the continent's 2022 energy crisis via a 6.3 billion euro capital injection to ensure security of supply.
It later bought a stake in EnBW's high-voltage power grid TransnetBW and is currently in talks to acquire the German division of Dutch grid company TenneT.
($1 = 0.9220 euros)