Poachers killed four white rhinos in a raid on a privately-run game reserve in northeastern Zimbabwe on New Year's day, the parks department said Friday.

Zimbabwe Parks and Wildlife Management Authority spokeswoman Caroline Washaya-Moyo said the animals' horns had been sawed off the carcasses, but were yet to be moved when rangers discovered the killings at the Thetford Estate in the farming town of Mazowe.

The raid raises fears that a rhino poaching epidemic in South Africa may be spreading to neighbouring countries.

"The animals comprised two adult males, one adult female and one sub-adult male and are valued at $480,000," Washaya-Moyo said in a statement.

"A total of eight rhino horns were recovered... as well as 18 spent cartridges fired from a suspected 308 hunting rifle or an FN automatic rifle."

She said Zimbabwe, with an estimated population of around 700 rhinos, lost 19 to poachers last year, a slight drop from 23 the previous year.

Poaching is rife in Zimbabwe's game reserves, fuelled by cross-border syndicates from Mozambique, Zambia and South Africa.

Perpetrators are armed with advanced technology and aircraft, often outstripping wardens' resources.

The rhino is targeted for its horn which is believed to be an aphrodisiac, anti-carcinogenic and an amulet in some Asian countries.

There is no scientific evidence to support those claims.

South Africa last year lost a record 633 rhinos to poaching.