"I want to congratulate President Trump on the impressive achievement of bringing about the elimination of al-Baghdadi," Netanyahu said on a visit to an Israeli air force base in remarks broadcast by army radio.

"This reflects the united resolve of the free countries led by the United States to fight the forces of terror, the terror organisations and the terrorist states," a later statement from the premier's office quoted him as saying.

"This is an important milestone, but it's part of a longer battle which we must win."

In August, Israel's Shin Bet security service said around a dozen Israeli Arabs were still fighting for IS in Syria and Iraq.

Trump said earlier that Baghdadi died "like a dog" in a daring, nighttime raid by US special forces deep in northwest Syria.

In a televised address from the White House Trump said that US forces killed a "large number" of Islamic State group militants during the raid which culminated in cornering Baghdadi in a tunnel, where he set off a suicide vest.

He said that the raid -- which required flying more than an hour by helicopter in both directions from an undisclosed base -- had been accomplished by help from Russia, Syria, Turkey and Iraq.

Trump's announcement came after Turkey on October 9 launched a military offensive into northern Syria to push Kurdish forces back from the Turkish border, after US forces left the area.

The US decision was seen as an abandonment of Washington's Kurdish allies.

The US pullout caused concern in Israel, where there were worries it too could be abandoned it by its most important ally.

There were also concerns archfoe Iran could seek to fill any resulting vacuum of power in Syria.