Beijing has expressed “grave concern” after the Islamic State (ISIS/ISIL) claimed responsibility for killing two Chinese nationals kidnapped in the Pakistan’s restive Balochistan province last month.

Both al-Qaeda and its rival ISIS have threatened Pakistan to attack China.

The ISIS-linked Amaq news agency reported Thursday that the jihadist group had murdered two Chinese teachers who had been kidnapped on May 24 by terrorists posing as police officers in Quetta, the provincial capital of Balochistan, home to various jihadist groups.

U.S., Indian, and Afghan officials have accused Pakistan of willingly providing shelter to Islamic extremist groups. Even Pakistan’s ally China has expressed concern over Islamabad’s “complicated relationship” with jihadist groups.

A video featured by Amaq purportedly shows two bodies with gunshot wounds bleeding on a grassy ground.

“We have taken note of relevant reports and we express our grave concern. We have been trying to rescue the two kidnapped hostages over the past days,” Hua Chunying, a spokeswoman for the Chinese Foreign Ministry, said in a statement. “The Chinese side is working to learn about and verify relevant information through various channels, including working with Pakistani authorities.”

“The Chinese side is firmly opposed to the acts of kidnapping civilians in any form, as well as terrorism and extreme violence in any form,” she adds.

Terrorists kidnapped the couple while they were teaching Chinese near the Pakistan’s border with war-ravaged Afghanistan.

China vowed to “take all necessary measures” to liberate the abducted Chinese nationals.

“The Chinese government has maintained close communication with Pakistan since the abduction took place and urged Pakistan to take all necessary measures to secure the early release of the hostages,” Lu Kang, a spokesperson for China’s Foreign Ministry, told reporters last month.

Balochistan, which makes up 44 percent of Pakistan’s territory, is a breeding ground for separatist Sunni jihadist groups who seek to establish their own state in a region that extends into neighboring Afghanistan and Iran.

ISIS has established its Khorasan branch in the area, named after an ancient region that covers parts of Afghanistan, Pakistan, Iran, India, and other surrounding countries.

Pakistani authorities reportedly raided ISIS jihadists last week while searching for the Chinese nationals. Although they killed several terrorists, the Pakistani security forces failed to find the teachers.

China had urged “Pakistan to take further steps to ensure the safety and security of Chinese nationals and institutions in Pakistan.”

“The Chinese government will work with the Pakistani side to spare no efforts to rescue the two nationals at an early date,” noted the Chinese foreign ministry spokesman in May.

Beijing’s $55 billion China-Pakistan Economic Corridor (CPEC), a component of the modern-day Silk Road, is expected to run through Balochistan to the dismay of some separatist terrorists in the region.

ISIS took hostage Chinese consultant Fan Jinghui in 2015, but Beijing refused to pay a ransom for him.