WASHINGTON (Reuters) - The United States on Thursday imposed sanctions on a leader of an al Qaeda-linked Islamist militant group in Mali and warned the influence of Islamic State in West Africa was on the rise even as it lost territory elsewhere.

The U.S. Treasury Department blacklisted Amadou Koufa, a Salafist preacher and a leader of Jama’at Nusrat al-Islam wal-Muslimin (JNIM), an al Qaeda affiliate in the Sahel region.

French officials last year had said the militant leader had died in a raid in the former French colony, but he appeared in a propaganda video in February.

U.S. sanctions block any assets Koufa may have under U.S. control and bar any persons or entities in the United States from any dealings or transactions with him.

Northern and central Mali saw an increase in “widespread terrorist activity” in 2018, according to the U.S. State Department’s annual global terrorism report.

“ISIS is an increasing threat in places like Afghanistan, in places like West Africa, Southeast Asia - there’s an active ISIS presence there as well,” a senior State Department official said on Thursday.

Islamic State, which declared itself a so-called “caliphate” in 2014, lost control in 2017 of Mosul in Iraq and Raqqa in Syria, and quickly thereafter almost all of its territory as a result of operations by U.S.-backed forces. Its leader, Abu Bakr al-Baghdadi, was killed last month in Syria in a raid by U.S. special forces.

U.S. officials in July added two other leaders of an al Qaeda affiliate in Mali to its global terrorism list.