In this April 22, 2021 photo, a pharmacist reconstitutes the Pfizer-BioNTech COVID-19 vaccine in Worcester, Massachusetts. (JOSEPH PREZIOSO / AFP)

MOSCOW - A Chinese diplomat here has urged the United States to cooperate with the international community on origin-tracing of COVID-19, instead of covering up information on its biological experiments.

"If the US indeed aspires for truth and transparency, they must agree to an international investigation on the coronavirus, identify the source of the epidemic in the US and the reasons for its incompetent response," Chinese Ambassador to Russia Zhang Hanhui said Wednesday.

Washington "has to answer the existing questions about biological experiments in the US and other countries, where the Americans also have a number of laboratories," he told a press conference.

ALSO READ: Chinese officials say WHO's tracing proposal 'unacceptable'

Washington scrupulously studied the situation in other countries but hid the situation of its own. Meanwhile, it displayed a non-scientific approach to researching the origins, Russian news agency Tass quoted Zhang as saying.

"This is a job for scientists, while the Americans posed this question and this task to their intelligence services -- for the CIA to determine the origins of the coronavirus," he said.

China has always upheld the principles of openness, transparency and cooperation on COVID-19 origins investigation, but some US politicians only doubted "the statements of scientists, contrasting them against conspiracy theories, therefore politicizing the matters of science," Zhang added.