Hackers claiming to be supporters of the Islamic State group on Wednesday hacked the website of the Britain-based Syrian Observatory for Human Rights, the head of the monitoring group said.

The Observatory, which has been tracking Syria's conflict since it started in March 2011, has been aggressively reporting over the past year on atrocities committed by the Islamic State extremists.

The cyberattack reflected the growing use of Internet — often a sophisticated tool used by the Islamic State and the Sunni militants' backers — since the IS declared an Islamic caliphate on the territories it captured in June 2014 in Syria and neighboring Iraq.

The Observatory chief, Rami Abdurrahman, said the hacking will not deter him from reporting on the violations carried out in Syria. He added that his activist group had received threats in the past from President Bashar Assad's government, as well as the Islamic State group and al-Qaida's affiliate in Syria, the Nusra Front.

"We will continue our work in monitoring and reporting all violations committed in Syria no matter what side is carrying them out," Abdurrahman said over the telephone. He added that if one day he is harmed, there are more than 230 activists working for the group throughout Syria who will continue the job.

The group's website was not opening on Wednesday afternoon.

Abdurrahman said the hackers put a photo-shopped photograph of him on the webpage. It shows him wearing an orange jumpsuit while a masked man in black stands behind him with a knife — something reminiscent of beheading photographs published by the IS in the past.

The Observatory reported Wednesday that IS beaded a man and two women in the eastern province of Deir el-Zour after they were accused by the militants of practicing sorcery.

This was not the first case of sorcery accusations by IS. Last week, the group was reported to have beheaded two couples after accusing them of practicing sorcery.

In fighting on the ground in Syria, government troops regained control of the Leiliyeh neighborhood in the northeastern city of Hassakeh that was captured by IS two weeks ago, Syrian state TV reported. Syrian troops have regained control of several neighborhoods that were captured by IS in Hassakeh recently.

The Observatory also said members of the main Kurdish militia, the People's Protection Units, or YPG, took back the northern town of Ein Issa, two days after IS fighters captured it.

YPG fighters have been on the offensive in northern Syria over the past month capturing a long stretch along the border with Turkey from the IS.

In a statement, YPG said 10 Kurdish fighters, including a woman, were killed in clashes with IS over the past few days in northern Syria. Kurdish women fighters have played a significant role in the Kurdish militia, contributing to the force's battlefield successes.