Three Chinese nationals have been charged in Tanzania for possessing 706 tusks from poached elephants, court officials said Saturday.

Police and wildlife officers have cracked down on suspected poachers amid a surge of killings of elephant and rhino in the east African nation, operating under what was reported to be a shoot-to-kill policy and making sweeping arrests.

The three accused -- Huang Gin, Xu Fujie and Chen Jinzhan -- were arrested a week ago in the port city of Dar es Salaam. They had hidden the tusks, weighing 1.8 tonnes and worth an estimated $3.1 million, in containers.

Police and court officials said the trio were posing as garlic importers and marine product exporters. Magistrate Isaya Arufani denied them bail and ordered the case be heard in the high court.

"This court lacks jurisdiction to preside over the case which is prosecuted under organised crime and economic sabotage," the magistrate said. The trio face a maximum sentence of 20 years if found guilty.

The lucrative Asian black market for rhino horn, used in traditional medicine, and ivory has driven a boom in poaching across Africa.

Tourism is a key foreign currency earner for Tanzania, especially wildlife safaris to its world-famous parks that include the Serengeti and Ngorongoro crater.

On Thursday President Jakaya Kikwete told parliament that a controversial anti-poaching operation -- dubbed "Operation Tokomeza", or "Operation Terminate" -- would continue despite protests over reports that police and wildlife officers were operating a shoot-to-kill policy.

The Tanzanian parliament had suspended the operation last week after lawmakers alleged a string of abuses, but Kikwete said abandoning the operation was tantamount to letting the poachers win.

On Saturday, Tanzania's main human rights group demanded the resignation of the country's tourism minister over the alleged murders of four people, among them a woman, during the anti-poaching crackdown.

The Legal and Human Rights Center, or LHRC, said the female victim was beaten to death by police who were conducting a search of her home, where they suspected her husband had hidden wildlife trophies.

"Since its launch, the operation has been characterised by flagrant violations of human rights and the Tanzanian constitution," a statement said.

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