"Our forces have entered the Giza al-Bahriya district, the last Daesh bastion in Sirte, from several directions in the face of fierce resistance by the terrorists," the press service said on its Facebook page.
In August, Libyan forces stated that 70 percent of Sirte was liberated from the Daesh. The operation has received aerial backing by US forces.
Libya has been in a state of turmoil since 2011, when longtime leader Muammar Gaddafi was overthrown after several months of civil war. The country was later contested by two rival governments, the internationally-recognized Council of Deputies and the Tripoli-based General National Congress.
On March 31, the long-anticipated UN-backed Government of National Accord in Libya started to perform its duties. The government has so far failed to unite the country.
The Daesh, which is a militant jihadist organization outlawed in many countries, including Russia, gained control over Gaddafi's hometown of Sirte in 2015, a year after seizing large parts of Syria and Iraq.