A joint team of the World Health Organization and Chinese experts on Tuesday said that there was not enough evidence to determine that the coronavirus spread in China’s Wuhan city before December 2019, reported AFP.

“There is no indication of the transmission of the Sars-Cov-2 [coronavirus] in the population of the period before December 2019,” said Liang Wannian, head of the China team, at a press conference.

Liang said that the virus that causes Covid-19 could have been circulating in other areas before it was identified in Wuhan, reported Reuters. The head of the China team said that studies showed the virus “can be carried long-distance on cold chain products”, pointing to a possible importation of the virus – a theory that China has pushed in recent months.

In an interview given to state-run Xinhua news agency on January 1, China’s Foreign Minister Wang Yi had claimed that the coronavirus pandemic was likely caused by outbreaks outside the country, in an attempt to change the narrative about the infection’s origin.

During the press briefing, Peter Ben Embarek, a virus expert from the WHO, said that their mission to identify the origins of the infection pointed to a natural reservoir in bats. Liang, however, said that while transmission from animals was the likely route for spread to humans, “the reservoir hosts remain to be identified”.

The expert team, which visited China in January, spent about one month in the country – two weeks in quarantine and the same on fieldwork. The team’s visit was delayed for a long time before they could visit Wuhan finally.

During the closely-monitored visit, reporters were largely kept away from the experts, but information found its way on Twitter and in interviews.

Before the inquiry had begun, questions were raised on the relevance of finding the source of the infection and there were fears of whitewash. The United States, which blames China for the spread of the infection, had urged the WHO team to conduct a “robust” inquiry, while Beijing had hit back asking not to “politicise” the investigation.

According to AFP, the team spent just an hour at the seafood market where many of the first reported clusters of infections emerged over a year ago. They seemed to spend several days in their hotel without going into the city and were visited by various Chinese officials. The team also went to an exhibition celebrating China’s recovery from the pandemic.

However, the team carried out research at the Wuhan virology institute, where they spent nearly four hours. The experts said that they met the Chinese scientists there, including Shi Zhengli, one of China’s leading experts on bat coronaviruses and deputy director of the Wuhan lab.

Beijing has regularly denied claims that the virus originated in the country. It had faced flak from the international community for allegedly covering up the transmission of the disease and for acting too slowly to stop its spread.

Chinese state-run media and officials have pushed alternate theories that the coronavirus could have entered the country through imported frozen food, linked the infection to the United States military and cited research suggesting cases in the US and Italy pre-date those in Wuhan.