DEIR AL-ZOR, Syria (Reuters) - The Syrian army field commander standing by the Euphrates River predicted that Islamic State militants would very soon be “purged” from its opposite bank.

Damaged pictures of Syria's president Bashar al-Assad and his father, former president Hafez al-Assad are seen on storage tanks in Deir al-Zor, Syria September 20, 2017. Picture taken September 20, 2017. REUTERS/Omar Sanadiki

“Their fate is hell and the Syrian army pursues its operations step by step until the total liberation of the city,” he told Reuters Television during a tour of areas of Deir al-Zor in Syria’s east recently retaken by the military and its allies.

Islamic State’s last major stronghold, the cities, towns and farms in the fertile strip along the Euphrates are fast becoming the focus of Syria’s war and a potential flashpoint for wider geopolitical tensions.

The Syrian army, supported by Russia and Iran-backed Shi’ite Muslim militias, reached its besieged garrison in Deir al-Zor this month after a long desert campaign and is now fighting to recapture the city and its environs.

It has also crossed the Euphrates, establishing a bridgehead opposite Deir al-Zor on the east bank, where Kurdish and Arab militias backed by a U.S.-led coalition are waging a rival campaign against Islamic State.

The risk of open conflict between the two offensives has mostly been avoided despite their proximity in campaigns further upstream in recent months, thanks to U.S.-Russian dialogue.

But new moments of friction have shown how the danger is rising as the fight against Islamic State nears its climax and both offensives race to secure ground in the oil-rich region.

The U.S.-led coalition this week accused Russia of targeting the Syrian Democratic Forces (SDF) alliance it backs, and Russia on Thursday accused the SDF of twice shelling the Syrian army, adding it would retaliate in future.

The field commander standing on the Euphrates riverbank did not address those issues, but he told Reuters the army would capture the villages opposite where he stood in al-Bughilia, an area close to where the SDF is operating.

Slideshow ( 11 images )

“Soon, the forces will be deployed toward al-Safira and al-Huseiniya and they will be purged of Daesh,” he said, using an Arabic acronym for Islamic State.

Syrian state news agency SANA reported on Thursday that the army had expanded its area of control on the east bank of the Euphrates and a military media unit run by the army’s ally Hezbollah said they had gained control of another village there.

REASSERTING PRESENCE AT EUPHRATES

Above the Euphrates at Deir al-Zor, Reuters photographs showed soldiers and journalists peering over a wall to take pictures of a river along which the Syrian army has only recently gained stretches of land after an absence of years.

On the other side of the pale water was flat farmland held by Islamic State. The army suddenly ordered reporters to leave the riverbank when soldiers noticed plumes of dust on the other side that might signal approaching militants.

A little way downstream, there was fighting on Sakr island, opposite Deir al-Zor’s southern quarters, and the al-Mayadin television channel showed live images of farmland where clashes were taking place, smoke rising among the trees.

In recaptured areas of the city, Reuters photographs showed signs of Islamic State’s recent presence. Its slogans were written on shopfronts. An armored vehicle, marked “Army of the Caliphate”, stood damaged.

“Daesh presents a fierce resistance and uses car bombs and heavy and medium weapons,” the field commander said.

“There is a decision from the political leadership and the military command in the army to battle and hunt Daesh, and end their presence in Deir al-Zor and beyond.”

When the morning Islamic prayer broke across the city, it was at times drowned out by the sound of warplanes flying above.

On the desert road back from Deir al-Zor to government-held areas in the west, a stream of military convoys was passing, according to the Reuters journalists.

With war coming to the east bank of the Euphrates, the convoys were carrying amphibious armored vehicles, bridge parts and boats.