The Islamic State group (IS) has released an audio message purporting to come from its leader, Abu Bakr al-Baghdadi.

In the message, the first since September last year, the voice addresses IS supporters.

Although the audio is undated, it appears to refer to recent events, including the detention of a US pastor in Turkey.

IS has lost most of the territory it once held across Syria and Iraq.

Last year it was forced out of its former strongholds of Raqqa and Mosul, from where Baghdadi announced the establishment of the group’s “caliphate” in 2014.

“For the Mujahideen [holy warriors] the scale of victory or defeat is not dependant on a city or town being stolen or subject to that who has aerial superiority, intercontinental missiles or smart bombs,” Reuters quoted the new audio statement as saying.

Baghdadi, who has a $25m (£19m) US bounty on his head, has been reported killed or wounded on a number of occasions.

Earlier this year, his son was said to have been killed in a “commando operation” in the Syrian province of Homs, according to IS media.

Meanwhile, a UN report earlier this month warned that between 20,000 and 30,000 IS militants remain in the two countries.