Tanzanian police said Sunday they had arrested four Chinese men after finding 11 rhino horns hidden beneath their car in one of the largest seizures in the east Africa country.

The four were arrested on Friday in the southwestern district of Mbeya after they crossed into Tanzania from neighbouring Malawi, a police statement said.

"An investigation is ongoing, and the suspects will soon appear in court," it said.

African rhinos have two horns, meaning the seizure represents the death of at least six animals.

Hundreds of rhinos are massacred every year for their horn, used in East Asia for its supposed medicinal qualities.

The latest tallies show the slaughter of rhinos has climbed to a new high. Last year saw a record 1,215 rhino killed for their horn.

Demand for the rhinoceros horn -- which is made of keratin, which is also found in hair and nails -- has boomed in Vietnam and China, where it is valued for its supposed medicinal properties.

The highest levels of rhino poaching takes place in South Africa, which is home to around 20,000 rhino, or 80 percent of the world population.

Poaching is rampant in east African nations including Tanzania and Kenya, but poachers there focus more on elephant killing.