Algerian state energy firm Sonatrach announced on Monday the discovery of an "important" deposit of gas condensate in the Hassi R'mel field in the Sahara desert.
"Sonatrach announced today that it has identified a significant potential of hydrocarbons, at the level of the Hassi R'mel exploitation perimeter," a statement by the firm said.
The deposit is estimated to have between 100 and 340 billion cubic metres of gas condensate, the statement said.
"These volumes constitute one of the largest revaluations of reserves in the last 20 years," it added.
Sonatrach plans to start operating the field in November, with production expected to reach 10 million cubic metres per day.
Algeria has proven natural gas reserves of about 2.4 trillion cubic metres and supplies Europe with about 11 percent of its gas imports.
Sonatrach said in February that it was prepared to increase supplies to Europe in the wake of Russia's invasion of Ukraine.
In May, the Algerian firm signed a memorandum of understanding with Italian giant Eni to boost gas exploration in the North African country.