BEIRUT — Kurdish children from the besieged Syrian town of Kobane were beaten with electrical cables and forced to watch beheading videos while held in captivity by Islamic State militants, an international rights group said Tuesday. The report by Human Rights Watch is the latest to document claims of atrocities and abuses by the Islamic State, including accounts of public executions of dozens of opposition fighters in Iraq in the past week. Human Rights Watch said the militants abducted about 250 children between the ages of 14 and 16 in May while they were returning from middle school examinations in the Syrian city of Aleppo. All of the children have either escaped from captivity or were released by the group, which held them at a school about 30 miles southwest of Kobane. Some of the children were traded for militants held by armed Kurdish groups opposing the Islamic State, Human Rights Watch said in the report, citing interviews in Turkey with four of the children. In September, Islamic State laid siege to Kobane, a Kurdish village that borders Turkey, killing an estimated 800 people as part of advances by the group in Syria and Iraq. Intensified airstrikes and reinforcements into Kobane have helped the Syrian Kurdish defenders keep the Islamic State from overrunning the city, but the militants have continued their siege. The Human Rights Report describes harsh conditions for the children, including being forced to attend religious seminars, allowed to bathe only once every two weeks and endured various kinds of punishment. One of the four children interviewed by the group described how Islamic State captors “used an electric cable to beat children on the hands, back, and soles of their feet, especially when they misbehaved.” They also were forced to watch videos of Islamic State fighters “in combat and beheading captives.” “This evidence of torture and abuse of children by ISIS underlines why no one should support their criminal enterprise,” Fred Abrahams, special adviser for children’s rights at Human Rights Watch, said in a statement using one of the acronyms for the Islamic State. The report comes as Iraqi Kurdish fighters from Iraq, known as peshmerga, have stepped up their role in Kobane after Turkey agreed to allow about 150 reinforcements to enter last week, bringing badly needed ammunition and artillery support. Rami Abdulrahman of the Britain-based Syrian Observatory for Human Rights said airstrikes killed at least 13 of Islamic State fighters since Monday and destroyed sites including a radio station controlled by the group. Meanwhile, the Observatory the Islamic State released 93 Syrian Kurds captured as it moved on Kobane, the Reuters news agency reported. The reason for the reported release was not immediately clear, but the Islamic State occasionally frees captives. Elsewhere in Syria, fighters linked to al-Qaeda held ground near a key Turkish border crossing after routing U.S.-backed rebels in battles over the weekend. The gains by Syria’s al-Qaeda affiliate, Jabhat al-Nusra, is a major setback for Washington’s Syria strategy of backing so-called “moderate” Syrian rebels as a proxy ground force against the Islamic State. Liz Sly contributed to this report.