Islamic State has been dealt twin blows, as Syrian troops announced they had retaken the last major city in the country’s eastern desert where the militants still had a presence, and Iraqi forces seized a crossing near the jihadis’ last urban bastion across the border.

The simultaneous assaults on Deir ez-Zor in oil-rich eastern Syria and al-Qaim in western Iraq on Friday dealt fresh losses to Isis in its former heartland, leaving Abu Kamal, on the Syrian side of the border as the last town of note under its full control.

The city’s fall marks another key defeat for the militants, who have in recent months lost most of the territory they seized in a lightning 2014 advance across Syria and Iraq that led to the declaration of their self-styled “caliphate”.

At its peak Isis controlled territory roughly the size of Britain but in October, it lost its one-time de facto Syrian capital Raqqa after an assault of more than four months waged by the US-backed Syrian Democratic Forces, a Kurdish-Arab alliance, after having lost its stronghold of Mosul in July.

On Friday, Syria’s army announced that its Russian-backed assault had recaptured all of Deir ez-Zor city, while Iraqi forces captured the Husaybah border post on the edge of the town of al-Qaim.

“The army forces … restored security and stability to all of Deir ez-Zor city,” a spokesman for the Syrian army command said in a statement broadcast live on state television.



“Deir ez-Zor represents the final phase in the complete elimination of Daesh,” the statement added, using the Arabic acronym for Isis.

The city “was the headquarters of the organisation’s leadership, and in losing it, they lose their capacity to direct terrorist operations,” the statement added.

State television said engineering units from the army were combing captured neighbourhoods to clear mines and other explosives.

Syrian forces entered Deir ez-Zor city in September, breaking an Isis siege of nearly three years on government-held parts of the provincial capital.

The battle has been ferocious, with heavy Russian airstrikes and Syrian artillery fire leaving much of the city in ruins.

A reporter contributing to Agence France-Presse inside the city on Thursday saw entire floors of buildings that had crashed on to those beneath, while on others, facades were completely blown away to reveal empty, destroyed interiors.

Trenches dug by Isis fighters were still visible, as were army minesweepers working to locate and defuse explosives laid by the jihadists.

Before Syria’s war began in March 2011 with anti-government protests, about 300,000 people lived in the city, the capital of Deir ez-Zor province along Syria’s eastern border with Iraq.

But in 2014, Isis jihadists seized the city and much of the surrounding province, including vital oil and gas fields that once served as a key source of revenue for the extremists.

Isis has now been driven from most of its strongholds in Deir ez-Zor, but it still controls over 35% of the province, much of it empty desert.

Its last major position is the town of Abu Kamal, though it also holds a string of smaller towns and villages and at least one oilfield, according to the Syrian Observatory for Human Rights.

Iraqi forces entered al-Qaim on Friday, quickly taking several districts, and also recaptured an important border crossing nearby, military commanders said.

Iraq’s Joint Operations Command said troops had “regained full control” of the Husaybah border post on the edge of al-Qaim after launching a push to oust the jihadists.

Government forces launched the operation last week to seize al-Qaim and its surroundings, a barren pocket of desert along the Euphrates river near the Syrian border.

The US-led coalition has said about 1,500 Isis fighters are left in the area, which it expects to be the scene of the “last big fight” against the group in Iraq.