The leader of the so-called Islamic State group, Abu Bakr al-Baghdadi, has called on Muslims to fight on - despite recent defeats.

In a purported new audio recording, Baghdadi offered greetings to Muslims for Eid al-Adha, a feast which is celebrated this week, suggesting the message was recorded recently.

He congratulated what he described as the "striking lions" behind recent attacks in Canada and Europe and called on followers to use bombs, knives or cars to carry out more attacks.

The recording, published by IS media wing al-Furqan, runs for about 55 minutes.

It is the first known to be released since another was broadcast in September last year, and comes as IS has lost most of its territory in Iraq and Syria.

Baghdadi, who declared himself ruler of all Muslims in 2014 after capturing Iraq's main northern city Mosul, is now believed to be hiding in the Iraqi-Syrian border region after losing all the cities and towns of his self-proclaimed caliphate.

Baghdadi also called on Iraqi followers to keep up attacks against Shia Muslims and what he described as apostates - a reference to Sunni Muslims fighting against his group.

He called on followers to remain loyal to the leaders of his movement and urged the citizens of Saudi Arabia, Bahrain and Jordan to overthrow their rulers.

Baghdadi, who has been pronounced dead or wounded on several occasions, is said to move around with only a small group of followers.

Originally from Iraq, Baghdadi has been dubbed the "most wanted man on the planet" and the United States is offering a $25 million reward for his capture.

Two recent reports by the United Nations and the US government suggest there may still be 30,000 IS fighters or supporters in Iraq and Syria.