China's embassy in the Central African Republic (CAR) has warned its citizens risk becoming "mining slaves" in the politically unstable nation's gold trade, as Chinese workers look to sub-Saharan Africa as jobs in the Asian giant's gig economy dry up.

Chinese nationals have been killed or kidnapped by armed groups and even their supposed business partners, while others were scammed out of large sums of money and deported for illegally mining, the embassy said in a statement on Thursday.

Workers from China have streamed into resource-rich sub-Saharan Africa chasing their fortune, as gold prices surge amid large-scale Chinese state-backed buying while jobs in China's construction sites and factories evaporate as the world's second-largest economy slows.

Alongside the Central African Republic, the nearby Democratic Republic of Congo, Ghana and Mali have become hotbeds of illegal mining, driven by lax regulation and weak enforcement.

"Chinese citizens engaged in gold mining operations in the Central African Republic face significant security risks," the embassy in Bangui said, warning that it had received reports of nationals having their documents confiscated, turning them into "mining slaves."

The embassy did not say how many Chinese nationals had sought work in CAR's illegal mines.

"Some were attacked and killed amid rampant anti-government militia activity, others were tragically ambushed after becoming entangled in conflicts between different forces and countries, and some succumbed to fatal illnesses like malignant malaria," the statement said.

"Others met violent endings through staged accidents like 'car crashes' or 'hangings' following disputes with fellow shareholders," the embassy warned.

The Central African Republic's embassy in Beijing did not immediately respond to a Reuters request for comment.

CAR has been in a state of civil conflict for more than a decade and is among the poorest countries in the world, but has abundant reserves of gold, diamonds and oil.

China, which has lent the country more than $26-million, rarely comments on other nations' affairs - a principle of non-interference analysts say is largely aimed at safeguarding its economic interests overseas.

That said, Beijing in recent years has stepped up its public diplomacy on protecting Chinese nationals overseas.

One of China's highest-grossing films, Wolf Warrior 2, centres on a former Chinese special forces soldier rescuing Chinese workers in a war-torn African country, ending with an image of a Chinese passport and the message: "Don't give up if you run into danger abroad. Please remember, a strong motherland will always have your back."

China has long deemed all areas outside the CAR capital Bangui "extreme high risk," and is urging its nationals to evacuate, while the US State Department maintains its highest "Do Not Travel" advisory.

"The thing I regret most in this life is not stopping my son from going to the Central African Republic to dig for gold," the Chinese embassy's statement quoted a grieving mother who lost her child as saying.