The leader of the Islamic State group has released a new message encouraging his followers to keep up the fight for the city of Mosul.
The Site Intelligence Group, a US organisation which monitors militant activity online, said the speech purporting to be from Abu Bakr al-Baghdadi was released in an audio recording late on Wednesday.
In it al-Baghdadi, who has reportedly not been heard from for more than a year, rallies his fighters and calls on them to obey orders while remaining resilient and steadfast.
He also urges others to carry out attacks in Saudi Arabia and Turkey in the message, which is more than half an hour long.
"Oh you who seek martyrdom! Start your actions! Turn the night of the disbelievers into day," he says.
"Totally decimate their territories and make their blood flow like rivers!"
The recording was the reclusive al-Baghdadi's first released message to supporters since Iraqi forces launched the battle to retake Mosul, the country's second-largest city, from IS.
The message is being seen as an attempt to stir up the same Sunni resentment which preceded the 2014 IS takeover of Mosul, a largely Sunni city in Shiite-majority Iraq.
Using a derogatory term for Shiites, he says followers of the Muslim sect want to "empty Iraq of Sunnis and replace them with the worst of people".
He calls on fighters to "respond to all attacks" and to "target all in their media and forces, and all who belong to them".
The message could not be independently verified but it was similar to recordings previously released by al-Baghdadi.
The Islamic State group is fighting to hold Mosul as Iraqi forces and allied Kurdish forces advance on the city with US-led coalition support.
The city of more than one million people and surrounding territory fell to IS fighters during a surprise attack in June 2014.
Al-Baghdadi visited Mosul after the takeover and declared an Islamic caliphate that at one point covered nearly a third of Iraq and Syria.