Chinese diplomats are reportedly urging local law enforcement in Nigeria to step up their investigation into the “cruel” murder of three Chinese factory workers whose burned corpses authorities recently found in Lagos, the African country’s most populous city, the South China Morning Post (SCMP) reported Sunday.

SCMP noted:

According to the official radio station of [China’s] Zhejiang province, the three Chinese victims were employees at a furniture factory in Nigeria’s largest city owned by a businessman from Ruian city and they were killed “in a cruel manner” on December 15. The three people went missing after dinner and their bodies were found the next day, the factory owner, surnamed He, told the station. Two of the victims, surnamed Zhang and Hong, came from Zhejiang province while the third, named Sun, was from Shandong.

“It took [local police] hours to find them, their bodies were badly burned. The way they were treated was extremely cruel,” the factory owner told the Chinese radio station.

On Saturday, the Chinese consulate-general reportedly said the circumstances surrounding the murders were “complicated” without elaborating further.

Chinese diplomats have reportedly urged Nigerian authorities to step up their probe into the murders.

Focusing on the continent’s rich natural resources to fuel its domestic economic growth, China has rapidly expanded its financial activities in Africa — particularly in Nigeria — and has invested broadly in infrastructure projects across the continent that will assist the Asian giant in achieving its goals.

Echoing independent assessments, the U.S. government have expressed concerns about China’s expansion in Africa, accusing Bejing of encouraging dependency among countries by using predatory lending practices “to mire nations in debt and undercut their sovereignty.”

An estimated one-third of Nigeria’s foreign investment originates in China, SCMP pointed out.

Hundreds of thousands of Chinese nationals have moved into Africa amid Beijing’s growing investments on the continent.

Citing Chinese ambassador to Nigeria Zhou Pingjian, the newspaper noted that “there are about 40,000 to 50,000 Chinese people” in Nigeria alone.

Last month, Nigerian President Muhammadu Buhari rejected criticism that his country is falling prey to China’s debt traps in Africa.

“Some of the debts incurred are self-liquidating. Our country is able to repay loans when due in keeping with our policy of fiscal prudence and sound housekeeping,” he claimed.

Some Nigerians, however, remain apprehensive about China’s debt-fueled projects in Africa.

“Lately there has not been positive sentiment about Chinese investment in Nigeria, especially as we look to cases like the [alleged] Zambian defaults,” Abas Idaresit, a Nigerian investor and entrepreneur, told Financial Times.

Beijing has emerged as the chief U.S. competitor in Africa, experts told U.S. lawmakers this month.