Fighting between the Taliban and ISIS in Afghanistan has significantly escalated in recent weeks, militants said, as they vie for control of the country's east.
The rival groups have launched a series of attacks on each other, as ISIS seeks to expand its foothold in Afghanistan and the Taliban seek to stamp out the new arrival.
The Taliban launched offensives late last month in parts of Kunar and Laghman, claiming they had cleared out bases of fighters swearing allegiance to ISIS leader Abu Bakr Al Baghdadi.
Those attacks came after the local ISIS franchise, known as Islamic State in Khorasan, claimed the suicide bombing of a gathering of Taliban members and local people in Nangarhar province during the three-day Eid ceasefire. Twenty five people were killed.
Hundreds of civilians fled the fighting between the groups in the remote mountainous province of Kunar as the two sides exchanged heavy weapons fire from high ground.
Dozens of fighters were killed or taken prisoner as the clashes carried on for several days in Chapa Dara and Watapur districts, local officials said. Local Taliban fighters were reportedly joined by reinforcements from neighbouring Nuristan and Laghman provinces.
Earlier this month ISIS then said it had blown up a Taliban vehicle in Nangarhar, killing several fighters.
"Yes the war between the Afghan Taliban and Islamic State branch in Khorasan has escalated," one ISIS source told The National. "More attacks and more casualties, but in war there are casualties."
The source, who spoke anonymously because he was not authorised to talk to the media, confirmed the Taliban had captured parts of Kunar and ISIS had seen “some setbacks”, but said: “They are not able to get firm control over the recaptured areas because soon they will be repelled back by the fighters of Islamic State.”
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ISIS arrived in the region in early 2015 when existing militants first swore allegiance to Islamic State in Iraq and Syria. From a stronghold in districts of Nangarhar province it has made inroads into other parts of the country and claimed responsibility for a series of deadly suicide bombings. Recent attacks have included a bombing in Jalalabad that killed 19 people, mostly members of the country's beleaguered Sikh minority, and a blast at a security checkpoint that killed 12. ISIS has grown its foothold in the country even as the group's self-proclaimed caliphate in Iraq and Syria has been largely swept away. The group is now the focus of US counter terrorism efforts in Afghanistan. Much of its growth has come from defections from other militant groups, particularly the Pakistan Taliban.
The militant group has also been at odds with the Afghan Taliban since its inception. The Taliban has said the group defames Islam and distracts from its own campaign against President Ashraf Ghani's international-backed government and to drive foreign troops from the country.
“The reason behind the escalation of recent attacks from both sides is due to Islamic State's quick expansion and control of more Taliban areas in the region,” the ISIS source said. “Islamic State will launch more attacks on the Taliban strongholds to capture more and more areas in order to expand the Islamic State in Khurasan.”
As well as Kunar, Taliban fighters have attacked ISIS positions in Alingar District of eastern Laghman province.
The Taliban have in the past been reluctant to publicise its clashes with ISIS, militant sources said, believing it risks exaggerating the power of the group.
But a Taliban source told The National: "The Taliban hit ISIS fighters hard and finished their presence in Laghman, while ISIS fighters were also killed in Kunar and Nangarhar. The Taliban will deal with them with an iron hand in future because they are exceeding their activities in the region".
The movement's priority remained attacks on US and international forces, but the emergence of ISIS had risked undermining its campaign, he said.
The Taliban source, who also asked to withhold his identity as he was not permitted to brief the media, said: “ISIS has presented a negative image of Islam and created an environment of fear among the Muslims.
He said ISIS attacked the Taliban “under the pretext of Islamic Shariah law and calling Taliban apostates thus creating confusion among the locals and other supporters of Afghan Taliban. In this way they are paving the way for the US and allied forces to create cracks in the unity of the Afghan Taliban, but so far they failed.”