The leader of the Islamic State terror group, Abu Bakr al-Baghdadi, is believed to have died in a US raid in north-western Syria overnight, intelligence officials have claimed.

The raid followed a month-long intelligence operation that had tracked Baghdadi to the region through a smuggler who had moved the wives of two of his brothers from Iraq to Idlib, two officials told the Guardian.

Donald Trump is due to make an announcement at 9am (1pm GMT) on Sunday in Washington, having tweeted on Saturday night without explanation: “Something very big has just happened!”

Intelligence officials believe Baghdadi may have detonated a suicide belt as troops approached a house near the Turkish border in which he was hiding. The blast is thought to have also killed two of his wives.

Explosions and gunfire were reported from the small town of Barisha at about 1.30am Syrian time on Sunday. It is understood that the Isis leader had been tracked to the home of one his bodyguards who attempted to defend him. The raid is thought to have left at least nine people dead.

Iraqi state television aired footage on Sunday that it said showed the raid.

Play Video 0:27 Footage appears to show aftermath of raid targeting Abu Bakr al-Baghdadi – video

If confirmed, the death would be a devastating blow to a terror group that had run rampant across the region for five years from mid-2014, spawning gruesome terror attacks across the world, amplifying a mass refugee exodus and sparking a war to contain them that killed thousands of people and displaced millions more.

Throughout that time, Baghdadi remained the face of Isis: a fearsome implacable ideologue who eluded the world’s intelligence agencies while continuing to incite a war of civilisations.

The Syrian Observatory for Human Rights, a war monitor, reported that a squadron of eight helicopters accompanied by a warplane belonging to the international coalition attacked positions of the Hurras al-Deen (an al-Qaida affiliated group) where Isis operatives were believed to be hiding in the Barisha area north of Idlib city.

Facebook Twitter Pinterest A Syrian man clears debris at the site of helicopter gunfire, which is thought to have killed nine people near Barisha. Photograph: Omar Haj Kadour/AFP via Getty Images

Over the past month, the manhunt for Baghdadi intensified after Iraqi officials identified a Syrian man who had moved his family members and wives from Iraq to Syria. An Iraqi intelligence official said the wives of Baghdadi’s two brothers, Jumah and Ahmad, along with other family members, were monitored as they moved to the region. The information was passed to the CIA earlier this month, the officials say.

Telegram accounts linked to Isis were on Sunday offering prayers for Baghdadi, but not confirming his death. The terror group no longer controls territory in Syria or Iraq after a five-year war across much of both countries.

Several Syrian rebel groups active in Idlib province say they had been asked by US officials over the past fortnight to establish whether senior Isis members were hiding in Idlib.

Iran said it had been informed by Syrian sources that Baghdadi had been killed, two Iranian officials told Reuters on Sunday. “Iran was informed about Baghdadi’s death by Syrian officials who got it from the field,” one of the officials said.

“Our sources from inside Syria have confirmed to the Iraqi intelligence team tasked with pursuing Baghdadi that he has been killed alongside his personal bodyguard in Idlib, after his hiding place was discovered when he tried to get his family out of Idlib towards the Turkish border,” one of the sources said.

On Saturday the White House spokesman, Hogan Gidley, said Trump planned to make a “major statement” on Sunday morning, but gave no further details. It was unclear what the topic of the president’s statement might be.

The region is mostly held by Hayat Tahrir al-Sham, an Islamist group that opposes Isis and routinely executes people thought to be affiliated with the group. Though long speculated to be a possible hideout, Idlib had been thought by many regional officials to be too risky a proposition for Baghdadi who was more accustomed to the deserts of Iraq, where his organisation had risen.

The death of Baghdadi would be a significant fillip for Trump, who has faced withering criticism from Republicans and Democrats alike for his troop withdrawal from north-eastern Syria, which permitted Turkey to attack the US’s Kurdish allies. He has also repeatedly insisted the US had defeated Isis – a claim denied by US generals and intelligence leaders.

Isis leader Baghdadi appears in video for first time in five years Read more

Many critics of Trump’s Syria pullout have expressed worries that it would allow Isis to regain strength and pose a threat to US interests. An announcement about Baghdadi’s death could help blunt those concerns.

Trump was expected to make the statement in the White House diplomatic reception room, which he has used to make a number of major announcements. Last week he used the same room to announce that a ceasefire between Turkey and the Kurds had taken hold.

For days, US officials had feared that Isis would seek to capitalise on the upheaval in Syria. But they also saw a potential opportunity, in which Isis leaders might break from more secretive routines to communicate with operatives, potentially creating a chance for the US and its allies to detect them.

Baghdadi, who has $25m bounty on his head, was long thought to hiding somewhere along the Iraq-Syria border. He has led the group since 2010, when it was still an underground al-Qaida offshoot in Iraq.

On 16 September, Isis’s media network issued a 30-minute audio message purporting to come from Baghdadi, in which he said operations were taking place daily and called on supporters to free women jailed in camps in Iraq and Syria over their alleged links to his group.

Facebook Twitter Pinterest Syrians ride a motorcycle past a burnt vehicle near the northwestern Syrian village of Barisha. Photograph: Omar Haj Kadour/AFP via Getty Images

In the audio message, Baghdadi also said the US and its proxies had been defeated in Iraq and Afghanistan, and that the US had been “dragged” into Mali and Niger.

At the height of its power Isis ruled millions of people in territory running from northern Syria through towns and villages along the Tigris and Euphrates valleys to the outskirts of the Iraqi capital, Baghdad.

But in 2017, the fall of Mosul and Raqqa, its strongholds in Iraq and Syria respectively, stripped Baghdadi, an Iraqi, of the trappings of a caliph and turned him into a fugitive thought to be moving along the desert border between Iraq and Syria.

US air strikes killed most of his top lieutenants, and before Isis published a video message of Baghdadi in April there had been conflicting reports over whether he was alive.

Despite losing its last significant territory, Isis is believed to have sleeper cells around the world, and some fighters operate from the shadows in Syria’s desert and Iraq’s cities.

The group claimed responsibility for a series of suicide bombings in churches and hotels in Sri Lanka that killed more than 250 people in April, though police in the Indian Ocean island country say they are yet to establish a direct link to the terrorist group.