The man and woman, said by Chinese media to be a couple, were kidnapped by armed men on May 24 from the city of Quetta, the capital of Pakistan's Balochistan province, on May 24 on their way to teach a Chinese language class, a senior security officer told CNN last month.
Amaq, a news agency affiliated with ISIS, said Thursday that Islamic State fighters had killed two Chinese teachers who were being held in the Mastung, Balochistan. The group also released a video, which showed two bodies shot and bleeding on some grassy ground.
"China resolutely opposes all forms of kidnapping of civilians and opposes all forms of terrorism and extreme acts of violence," said Hua Chunying, the spokesperson for China's Foreign Ministry, in a statement on Friday.
Pakistan's Ministry of Foreign Affairs said it was "working to confirm authenticity of the reports of killing of two Chinese nationals, kidnapped in Quetta."
The deaths underscore the risks of China's growing international reach and influence. The Global Times, a state-run tabloid, said that guarding Chinese nationals overseas had become a new and serious challenge for national security.
"As China's international influence is growing, terrorist organizations target Chinese for ransom or just to create a sensation. Cases of Chinese being kidnapped have increased," the paper said in an editorial.
Chinese nationals have settled in Pakistan in greater numbers since the announcement of a $46 billion investment plan known as the China-Pakistan Economic Corridor (CPEC) in 2015 -- part of China's One Belt One Road initiative.
"Given Pakistan's complex security situation, both sides need to study and formulate a more comprehensive security plan to fully cover Chinese in Pakistan," the Global Times added.
Hua said authorities had been trying to rescue the hostages.
Pakistan's military said Thursday that its security forces conducted an operation from June 1 to 3 in Mastung, where it said it killed 12 terrorists with links to ISIS that had been hiding in caves but didn't mention the abducted Chinese teachers.
Balochistan is home to the Gwador Port Complex, a flagship project of the economic corridor, but has been plagued by violence by different militant groups including the Pakistani Taliban and a separatist movement.
Pakistan views CPEC, a combination of infrastructure projects ranging from road networks, a fiber optic cable project, railway lines, a deep-sea port, coal mines and solar farms, as a huge opportunity to develop its economy.
Pakistan is home to roughly 20,000 Chinese, according to Mustafa Hyder, chief executive of the Pakistan-China Institute.