MANILA - Philippine government forces in war-torn Marawi city are preparing for a final assault against the Maute terrorists with the hope of ending the battle soon.

"Our troops are preparing for final assault," Philippine Star quoted Defence Secretary Delfin Lorenzana as saying on Sunday (Aug 27).

When asked about a target date for the final assault, he said the decision lies with the ground commanders and the troops in the battleground.

The military has been battling the Maute terrorists to retake Marawi city for almost 100 days. The fighting has claimed the lives of 130 soldiers and policemen, while at least 603 terrorists have been killed, the Philippine Star reported. Civilian casualties remain at 45.

Authorities took over the city's police headquarters from the extremists last Thursday while the Grand Mosque was recaptured the following day, said the report.

The extremists had used the Grand Mosque, located downtown, as a strategic post, and other mosques in the city as machine gun and sniper nests.

Some 1,000 militants seized large parts of Marawi on May 23 in an audacious bid to turn it into a "province" of the ultra-radical Islamic State in Iraq and Syria (ISIS).

The army, backed by bombers, helicopter gunships and US surveillance planes, have since boxed the gunmen inside half-a-square kilometre area, and whittled their number to just 50 to 60.

The attack forced Marawi's entire population of over 200,000 to evacuate, and the ensuing battle levelled more than half the city, including its once-thriving commercial centre. Marawi itself is still closed to civilians.