At least 72 civilians who had been prospecting for gold in a border region of Sudan have been killed in air strikes, a regional rights group says.

Emergency Lawyers, based in the Sudanese capital, Khartoum, said jets targeted the so-called artisanal miners at a popular gold mining site in Sudan's River Nile state on Saturday.

Neither the Egyptian government nor the de facto Sudanese authorities have commented so far.

Cairo has previously faced accusations of deadly strikes on gold prospectors as part of a crackdown on illicit activity along its southern border.

Emergency Lawyers noted the previous alleged attacks and said they represented not only a violation of Sudan's sovereign territory but also demonstrated the government's lack of control over the region.

"The deliberate targeting of unarmed civilians violates international humanitarian law and the right to life," it said in a statement on Sunday. "These acts may constitute war crimes."

It noted that its death toll was provisional and could rise.

The Paris-based Sudan Tribune reported that the death toll could far exceed the number reported by Emergency Lawyers, citing a survivor of Saturday's attack who said many more people had been injured.

Eyewitnesses said the attack began around 06:00 local time (04:00 GMT), with the aircraft firing more than five missiles directly at the miners' camps, destroying them and excavation pits with people still inside, the newspaper wrote.

The Sudan Tribune reported claims in June that Egyptian forces had used drones and artillery to target artisanal mining sites in the same region, killing several, after sporadic incidents of Egyptian border guards of burning equipment, torching temporary shelters, and firing live ammunition to disperse mine workers.

Days later, Egypt's border agency announced that it and the military had begun a sweeping security campaign along the border to foil illegal migration, drug smuggling and illegal mining.

At the same time, Sudan's de facto leader announced an investigation into the alleged strikes, which were said to have killed dozens.

Gold lies at the core of the border tensions.

Sudan's ongoing civil war has led to a surge in artisanal mining - an often risky practice conducted by civilians with rudimentary tools and without official permission - particularly in remote areas near its borders.

Gold-rich areas such as those in River Nile state lie along porous borders in terrain historically associated with cross-border smuggling routes, with artisanally mined gold potentially feeding into those channels.

Egypt's border force said in June that it had seized 86 tonnes of gold ore along with amateur prospecting equipment.

Artisanal mining has also reportedly continued in Sudan's conflict zones, and smuggled gold may be a source of income for armed insurgent groups.

This has raised concerns that illicit Sudanese gold is undermining the legitimate Egyptian gold market.