The so-called Islamic State threatens to seize Libyan oil refineries — and gain a major new revenue source — as the terror group expands its presence in the war-torn country.

IS fighters have pushed toward critical port facilities near their Libyan stronghold of Sirte, according to a senior State Department official who was not authorized to talk publicly about the issue and asked not to be named, US Today reported on Wednesday.

Secretary of State John Kerry said Tuesday that the United States and its allies have made progress against the Daesh in parts of Iraq and Syria but are concerned the militant group has spread into Libya.

"That country has resources,” Kerry said. “The last thing in the world you want is a false caliphate with access to billions of dollars of oil revenue."

Kerry spoke in Rome where a coalition of 23 nations met to review their strategy to defeat the IS, also known as ISIL or ISIS.

The militants are attempting to expand into Ras Lanuf and Brega, large refinery and export facilities east of Sirte, the State Department official said. Ras Lanuf came under attack by militants last month in fighting that touched off a large fire.

The ports are no longer used to export oil, but the refineries there can process domestic supplies and store oil.

Source: MENA