Germany's Uniper said on Wednesday the government could take a controlling stake in the company as the utility seeks further aid, sending its shares tumbling 20%.

After Moscow slashed gas flows to Germany, Uniper has been forced to burn through its cash reserves sourcing expensive alternative supply on the spot market.

"The parties are looking into alternative solutions, inter alia a straight equity increase that would result in a significant majority participation by the German Government," Uniper said in a statement.

In July, Berlin said it would take a 30% stake as part of a rescue of Germany's largest importer of Russian gas.

Bloomberg reported earlier in the day that the government could take a stake of more than 50%, citing sources familiar with the matter.

No decisions have been made beyond what was agreed in July, Uniper said on Wednesday.

The company has already secured 13 billion euros of credit lines from the state, most of which it has already drawn. Last month it asked for more state help, raising the bill for its bailout to 19 billion euros ($19.04 billion).

Uniper shares were at an all-time low of 3.87 euros at 1145 GMT.

The economy ministry said it was in talks with Uniper, and Finland's Fortum, Uniper's largest stakeholder, also said talks with the German government continued.

"We want discussions to be successful, which is why we are not commenting," a spokesperson for the ministry said.

Uniper CEO Klaus-Dieter Maubach in July flagged the possibility that the German government could end up holding more than 50% of the company.

"Nationalisation is the only solution left, Uniper's capital resources are totally under water. Mathematically speaking, there is nothing else that could be done," a source close to the matter told Reuters.The state will take more than a 50% stake, likely even full ownership, the source said, adding there were few alternatives left.

The head of Uniper's workers' council said it would welcome the government taking a majority stake, noting the security it would provide to the workforce.

The cost of replacing falling gas imports from Russia's Gazprom after Moscow's invasion of Ukraine pushed Uniper to a loss of 12.3 billion euros in the first half of the year.

The company is weighing legal proceedings before a Swedish arbitration court to claim billions of euros in compensation from Gazprom over what it says are unjustified gas supply cuts, two people familiar with the matter told Reuters.

($1 = 0.9979 euros)

The logo of German energy utility company Uniper SE is pictured in the company's headquarters in Duesseldorf
Germany