Islamic State leader Abu Bakr al-Baghdadi called for attacks against the rulers of Saudi Arabia in a speech purported to be in his name on Thursday, saying his self-declared caliphate was expanding there and in four other Arab countries.
Baghdadi also said a U.S.-led military campaign against his group in Syria and Iraq was failing and he called for "volcanoes of jihad" the world over.
Reuters could not independently confirm the authenticity of the speech - an audio recording carried on Islamic State-run social media. The voice sounded similar to a previous speech delivered by Baghdadi in July in a mosque in the Iraqi city of Mosul, the last time he spoke in public.
The speech followed contradictory accounts out of Iraq after U.S. air strikes last Friday about whether he was wounded in a raid. U.S. officials said on Tuesday they could not confirm whether Baghdadi was hit in a strike near Falluja in Iraq.
In Washington on Thursday, State Department spokeswoman Jen Psaki said she could not confirm the recording's authenticity and said Washington and others were likely to increase efforts to counter the group’s claims to represent Islam.
"Clearly the brutality, the rhetoric, the efforts to incite, by any leaders of ISIL … is not a new phenomenon. It certainly is a reminder to everyone in the region and around the world of what their intentions are," Psaki told reporters.
Baghdadi urged supporters in Saudi Arabia, the world's top oil exporter, to take the fight to the rulers of the kingdom, which has joined the U.S.-led coalition in mounting air strikes against the Islamic State group in Syria.
"O sons of al-Haramayn...the serpent's head and the stronghold of the disease are there...draw your swords and divorce life, because there should be no security for the Saloul," Baghdadi said, using a derogatory term to refer to the leadership of Saudi Arabia.
Haramayn is a reference to the two holiest places in Islam, both of them in Saudi Arabia.
Since Islamic State began an offensive in Iraq in June, Saudi Arabia has sent thousands of troops to the border area.
The speech was not dated but carried a reference to a Nov. 7 U.S. announcement that President Barack Obama had approved sending up to 1,500 more U.S. troops to Iraq. Obama has said the United States aims to degrade and eventually destroy Islamic State.
Islamic State has seized swathes of Syria and Iraq and in June declared a caliphate over territory it controls. Baghdadi said he had accepted oaths of allegiance from supporters in Libya, Egypt, Yemen, Saudi Arabia and Algeria.
"We announce to you the expansion of the Islamic State to new countries, to the countries of the Haramayn, Yemen, Egypt, Libya, Algeria," Baghdadi said. The speech was transcribed in Arabic and translated into English.
Although supporters have pledged allegiance to Islamic State in countries including Lebanon, Pakistan and Afghanistan, Baghdadi singled out only those five states, picking countries where sympathisers have a strong base and could mount attacks.
He added, however: "Oh soldiers of the Islamic State...erupt volcanoes of jihad everywhere. Light the earth with fire against all dictators."
Referring to U.S.-led military action against his group, Baghdadi said: "Despite this Crusade campaign being the most fierce and severe of all, it is the greatest failure."
"We see America and its allies stumbling in fear, weakness, impotence and failure."
Referring to Yemen, where Shi'ite Houthis captured the capital Sanaa in September, forcing the government to resign, he said: "Oh soldiers of Yemen...be harsh against the Houthis, they are infidels and apostates. Fight them and win against them."
Baghdadi also congratulated supporters in Egypt's Sinai for starting jihad against what he called the "dictators of Egypt". He also urged supporters in Libya, Algeria and Morocco to prevent secular groups from ruling.
After Baghdadi's speech, Egyptian militant group Ansar Bayt al-Maqdis, which swore allegiance to Islamic state this week, changed its name to Sinai Province on the Twitter feed claiming to represent it.