FRANKFURT- Germany's energy network regulator on Friday said it would ensure ongoing operations at Gazprom Germania, a trading, storage and transmission business abandoned by Russia's Gazprom, and called on market operators not to cut ties.

With assets and subsidiaries in Germany, Britain, Switzerland, Belgium, the Czech Republic and outside Europe, the firm's activities are essential for the European gas market and its supply to industry and households.

"The Bundesnetzagentur will ensure that all payments of Gazprom Germania GmbH may only be made to maintain business operations and will thus prevent an uncontrolled outflow of funds," the German regulator said in a letter to operators connected with Gazprom Germania and seen by Reuters.

Spokespeople for the authority confirmed the letter had been posted.

"It will also ensure that the company can, and will, meet its payment obligations to continue its business operations," it added.

Gazprom Germania GmbH was taken into the regulator's control on April 4 as the Economy Ministry sought to stave off a possible acquisition by JSC Palmary and Gazprom Export Business Services LLC, both of Russia, the Economy Ministry said at the time.

Acquisitions of critical infrastructure by operators from outside the EU are prohibited under German foreign trade law, unless reviews allow it.

Its operations, based on Russia's gas production, span supplies to wholesalers and retailers, storage and pipeline transmission, covering the entire gas value chain.

Its operations include Germany's biggest gas storage facility at Rehden in Lower Saxony, with 4 billion cubic metres of capacity.

The regulator, in its letter addressed to banks, business partners, services providers and customers, said the company needed to procure gas and have the means to pay for it, avoiding insolvency.

"The consequences (of an insolvency) for the energy supply system, not only in Germany but in Europe as well, would be severe," it said.

Trading firms could collapse, transport would be disrupted, and underground storage caverns would remain unfilled, it said.

The April 4 move by the authority means it can remove executives, hire staff and direct management, as well as guarding against an outflow of finances.

(Reporting by Vera Eckert and Tom Kaeckenhoff; Editing by Maria Sheahan, Jason Neely and Jan Harvey)