BENGHAZI, Libya – Libya’s pro-government forces fighting to dislodge the Islamic State group from its key bastion of Sirte seized the city port on Friday as a Libyan spokesman said the group’s leaders have fled the city to the open desert south of Sirte.

Brig. Gen. Mohammed al-Ghasri also confirmed that foreign army experts including Americans and British are providing support to the forces battling the IS militants.

“The British and U.S. experts are helping us with logistical and intelligence to deal with Daesh suicide bombers and with tactical and strategic planning,” he told The Associated Press.

Al-Ghasri said initial intelligence showed that top group leaders have fled but a strong majority are cornered inside the city centre.

Earlier, a media official said that the forces have found bodies of militants, handcuffed and shot in the head, inside army barracks in the city.

Ahmed Hadiya told the AP that at least six bodies were found inside the al-Saadi barracks after the facility was overrun by the forces allied to the U.N.-brokered government. He said he believes the bodies are of IS “militants who wanted to flee.”

He added that the offensive to capture the Mediterranean city is nearing its “final stage” and that IS fighters have hunkered down inside a sprawling convention centre for the final showdown.

The fighting, which started a month ago, is led by militias from the western city of Misrata, west of Sirte. The fighters advanced from the western and southern fronts and are currently besieging the militants from all directions, including the eastern front, after taking over the port located to the east of the city centre.

Battles are underway near the main city hospital of Ibn Sina and the IS headquarters inside a sprawling convention centre.

IS took over Sirte last year exploiting Libya’s turmoil to gain a foothold in the North African country.