Eni said it joined state-run energy company Sonatrach in starting production at the field about 600 miles from Algiers.
A plant on site will allow Eni to treat natural gas for the production and sale of 317 million cubic feet of natural gas, 15,000 barrels of oil and condensate and 12,000 barrels of propane.
"With the start of production at the MLE field and other projects, Eni strengthens its presence in the country, and expects to achieve a daily equity production of 100,000 barrels of oil equivalent in 2013," the company said in a statement.
Militants sympathetic to al-Qaida in the Islamic Maghreb last month attacked the Ain Amenas natural gas facility in eastern Algeria. The site is operated by BP, Norwegian major Statoil and Sonatrach.
Algerian Prime Minister Abdelmalek Sellal last week said the dead included 37 people, from eight countries, including three from the United States, and 29 abductors.
Eni's announcement made no reference to the Ain Amenas attack or national security.