South Korea's Celltrion Inc says its experimental treatment for COVID-19 has shown a 100-fold reduction in the viral load of the disease during animal testing.

The pre-clinical study of the drug showed improved recovery in runny nose, cough and body aches after the first day of treatment, and clearing of lung inflammation within six days, the company said in a statement.

Celltrion has research experience with other types of coronavirus conditions such as Middle East Respiratory Syndrome (MERS). It hopes to start first in-human clinical trials for the COVID-19 treatment in July, said Kwon Ki-Sung, head of the firm's research and development unit.

"(Celltrion) has the capability to roll out mass production of the therapeutic antibody treatment once it is ready," Kwon said.