A major increase in violence by the Islamic State group saw over 1,000 attacks and nearly 3,000 deaths worldwide in the past three months, analysis firm IHS Jane's said Thursday.
The figures show a 42-percent jump in daily attacks by the jihadist group, averaging 11.8 per day from July to September, up from 8.3 per day between April and June.
The figures suggest that air strikes by the US-led coalition have had only a limited impact on the group.
The London-based analysis firm recorded 1,086 IS attacks, causing a total of 2,978 civilian and government fatalities -- a huge 65.3 percent increase in the average daily killings by the group compared to the previous three months, and an 81 percent jump on one year earlier.
IHS Jane's Terrorism and Insurgency Centre uses open sources to compile their database, and said IS likely carried out far more attacks that could not be verified.
"While the airstrikes and wider coalition efforts have put the group under significant pressure, it is seemingly still some way from being sufficiently weakened to allow the recapture of territory, let alone be defeated," Matthew Henman, head of the Terrorism and Insurgency Centre, told AFP.
Russia's increased involvement in Syria in recent weeks is likely to further strengthen IS, since there was a "clear indication" that Moscow is more interested in defending the Syrian regime than defeating IS.
"Already over the past week the Islamic State has made gains in areas of Aleppo governorate due to the targeting of rival opposition groups and this is likely to continue," said Henman.
"Civilian deaths in Russian airstrikes also give the Islamic State a powerful propaganda tool."
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- Boko Haram's contribution -
The figures reflect the inclusion of Nigeria's brutal Boko Haram militant group, which declared allegiance to IS in March.
Renamed Wilayat Gharb Afriqiyah, the group's attacks were the deadliest of any IS affiliate.
"This underlines the nature of the group's insurgency in Nigeria and several bordering countries, with its operations characterised by mass-casualty operations targeting the civilian population in the group's northeast operational heartland," Henman said.
The new figures also reflect changes in the type of combat over the summer in Iraq and Syria, which still account for the vast majority of IS activity.
After capturing some key areas -- including the Iraqi city of Ramadi and Syria's Palmyra earlier this year -- the group focused on defending them from government forces and rival insurgent groups.
This meant an increase in "frequent, low-level, close-quarters engagements", rather than the previous focus on mass-casualty attacks used to seize territory.
Overall, IS did not make any major territorial advances during the three-month period, though it did announce a new branch -- known as a "wilaya" -- in Saudi Arabia in August.
It has previously announced wilayas in Afghanistan-Pakistan, Algeria, Egypt, Libya, Yemen, Russia's North Caucasus and Nigeria, in addition to the group's operational heartland in Iraq and Syria.