By Joyce Lee and Heekyong Yang

SEOUL (Reuters) - South Korea's Celltrion Inc <068270.KS> said on Monday its experimental treatment of COVID-19 demonstrated an up to 100-fold reduction in viral load of the disease in animal testing, saying it aims to start in-human clinical trials in late July.

Drugmakers worldwide are rushing to develop treatments for the flu-like illness that has caused more than 371,000 deaths globally.

Celltrion said its pre-clinical study 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 study was conducted with ferrets and will be expanded to hamsters, mice and monkeys before clinical trials, Celltrion and study collaborator Chungbuk National University College of Medicine said in a statement.

Celltrion is considering running clinical trials in South Korea or abroad, Kwon Ki-sung, head of Celltrion's R&D unit, told Reuters.

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

Celltrion stock was up 6.3% versus the benchmark KOSPI's <.KS11> 1.4% as of 0420 GMT.

President Moon Jae-in in April pledged 210 billion won ($171 million) in funding to develop COVID-19 drugs, hoping to replicate the country's success in COVID-19 test kits.

Rigorous testing and tracking was instrumental in bringing the novel coronavirus virus under control in South Korea, which at one point experienced the biggest outbreak outside China, where the virus was first reported.

South Korea on Monday reported 35 new cases, bringing its total to 11,503.

U.S drugmaker Gilead Science Inc <GILD.O> has reported promising early trial results for its treatment remdesivir, prompting emergency approval in the United States and Japan. South Korea also said last week it would request imports of remdesivir.

Other South Korean pharmaceutical firms such as SK Bioscience and Green Cross Corp <006280.KS> are at the beginning stage of coronavirus vaccine development.

SK Bioscience last month received $3.6 million in research funding from the Bill & Melinda Gates Foundation to develop a COVID-19 vaccine.

(Reporting by Joyce Lee and Heekyong Yang; Additional reporting by Hyunjoo in; Editing by Himani Sarkar and Christopher Cushing)