The Islamic State jihadist group has announced plans to halve the monthly salaries of its members in Syria and Iraq as the economic reality of waging war on several fronts takes its toll.

The Syrian Observatory for Human Rights, which relies on a network of activists, medics, and fighters across Syria for information on Isis, published what it said was an official statement from the militant group announcing the cuts.

“Because of the exceptional circumstances that the Islamic State is passing through, a decision was taken to cut the salaries of the mujahedeen in half,” the Arabic statement said.

“No one will be exempt from this decision no matter his position, but the distribution of food assistance will continue twice a month as usual,” it said.

Isis has declared a self-styled “caliphate” across swaths of territory in Iraq and Syria, imposing its harsh interpretation of Islamic law.

According to Observatory head Rami Abdel Rahman, the salary cuts meant Syrian Isis fighters would see their salaries drop to about $200 a month.

Foreign fighters, who were paid double the Syrian militants, would have their monthly income reduced to $400, Abdel Rahman told AFP.

The jihadist group strives to show that it operates a full-fledged state, with government institutions, hospitals, and schools.

The financial strain could be a result of intensified air strikes on its oil infrastructure in Syria and Iraq.

A US-led coalition is conducting an air war on the group in both countries, and Russian warplanes are also targeting the jihadists in Syria.

The Observatory also noted that Isis has released 270 of an estimated 400 civilians, most of them women and children, who were kidnapped at the weekend when its fighters attacked Syrian government-held areas in the eastern city of Deir al-Zor.

The Observatory said, however, that the ultra-hardline group rounded up another 50 men on Tuesday during raids on houses in areas seized during four days of fighting in the provincial capital.

Rami Abdulrahman, the Observatory’s head, said that the group has kept male prisoners between the ages of 14 and 55 for more questioning.

“Those who they see have ties with the regime will be punished and those who (do) not must undertake a religious course based on the group’s interpretation of Islam,” he said.

The civilians released will remain in Islamic State-run villages in the province of Deir al-Zor, which links the group’s de facto capital in Raqqa with territory controlled by the militant group in neighbouring Iraq.

The group, which controls of most of the province, has laid siege since last March to remaining government-held areas in the city of Deir al-Zor.