In this Wednesday, March 22, 2017 photograph, a pilot prepares to fly an F-18 off of the USS George H.W. Bush as it travels through the Persian Gulf. The carrier soon will begin launching airstrikes targeting the Islamic State group in Iraq and Syria. (AP Photo/Jon Gambrell)

BEIRUT - U.S.-backed Syrian fighters reached a major dam held by the Islamic State group in northern Syria Friday as Syria's U.N. ambassador said hundreds of American personnel are "invading my country," insisting that any effort to liberate the city of Raqqa — the de facto capital of the Islamic State group — should be done in co-ordination with the Damascus government.

The push toward the Tishrin Dam came three days after U.S. aircraft ferried Syrian Kurdish fighters and allies behind IS lines to spearhead a major ground assault on the IS-held town of Tabqa where the dam is located. Tabqa is west of the city of Raqqa.

IS has been pounded in Syria in recent months with attacks against the extremists from three fronts, the U.S.-backed fighters, Turkish troops and their allies near the border with Turkey, and government forces in the northern province of Aleppo.

The government-controlled Syrian Central Military Media said government forces captured late Friday the town of Deir Hafer, the last IS stronghold in Aleppo province, after troops stormed the town under the cover of Russian airstrikes.

After losing wide areas they once held in Syria, IS extremists now are mostly present in the northern province of Raqqa and the eastern region of Deir el-Zour that borders Iraq.

Cihan Sheikh Ehmed, the spokeswoman for the Syrian Democratic Forces, said the fighting is ongoing at the entrance of the dam, adding that there have been casualties among IS fighters. She gave no further details.

The Britain-based Syrian Observatory for Human Rights said SDF fighters are marching slowly toward the buildings of the Tishrin Dam because of mines and explosives planted by IS.

To the east of Raqqa, SDF fighters clashed with IS gunmen inside the village of Karama, according to the Observatory and Mohammed Khedhr of Sound and Picture Organization, which documents IS violations. Karama is about 15 kilometres (10 miles) east of Raqqa, making it a strategic village to capture.

The attacks on the Tabqa and Karama were ongoing under the cover of airstrikes by the U.S.-led coalition, according to the activists.

SDF fighters have been on the offensive since November under the cover of airstrikes by the U.S.-led coalition with the aim of eventually surrounding Raqqa and storming it.

In France, the country's defence minister said the campaign by international forces to take back IS' de facto capital will start in the coming days. Defence Minister Jean-Yves Le Drian said Raqqa is a "major objective" for the U.S.-led coalition trying to quash IS extremists in Syria and Iraq.

Le Drian spoke on CNEWS television Friday. He said: "Today we can say that Raqqa is encircled and that the battle will begin in the coming days. It will be a very hard battle but it will be an essential battle."

As the coalition advances in its battle to retake the IS stronghold of Mosul in Iraq, the U.S. has been intensifying involvement in Syria's conflict ahead of the battle for Raqqa.

In Geneva, where peace talks between the Syrian government and opposition resumed Friday, Syria's ambassador to the U.N. Bashar al-Ja'afari insisted that "American warplanes" had bombed a school in the village of Mansourah, west of Raqqa, a day earlier and were responsible for the deaths of 237 civilians among some 500 people fleeing Raqqa. He did not elaborate.

Al-Ja'afari said any military presence in Syria without government approval was "illegitimate."

Using the Arabic acronym for the Islamic State group, he said: "Those who are truly fighting Daesh are the Syrian Army with the help of our allies from Russia and Iran."

The U.S. has deployedmore than700 advisers, marines and Rangers to Syria to support fighters battling Islamic State militants.

Speaking to reporters later Friday, U.N. Special Envoy to Syria Staffan de Mistura told reporters that he is not expecting miracles, breakthroughs, or even breakdowns, at the latest round of Syria peace talks in Geneva.

De Mistura also urged Russia, Turkey and Iran, the guarantors of the upcoming talks at the Kazakh capital of Astana, to "retake the situation in hand" amid a recent escalation of fighting on the ground. The guarantors had successfully negotiated a cease-fire at the previous Astana talks, albeit one that De Mistura conceded has been violated repeatedly.

"Hopefully there will be a new Astana meeting as soon as possible to control the situation, which at the moment is worrisome," said De Mistura.

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Keaten reported from Geneva.

News from © The Associated Press, 2017