(Yicai Global) May 11 -- Shares of Runda Medical Technology tumbled after the Shanghai bourse asked the major lab service provider to explain why the accuracy of its Covid-19 testing has been questioned.

Runda's stock price [SHA: 603108] dived 5.9 percent to close at CNY10.94 (USD1.60) after dropping by the daily limit of 10 percent yesterday. The shares are more than 20 percent down in value this year.

The Shanghai Stock Exchange today issued a letter to the Shanghai-headquartered medical firm and requested it, as well as its directors, supervisors, and senior managers, to respond to questions raised by Yicai Global's media report from yesterday.

Yicai Global reported that residents in a neighborhood in Shanghai suspected that Zhongke Runda Precision Medical Inspection's Covid-19 test results were inaccurate as 13 samples in the neighborhood were proven negative by hospitals after first testing positive at Zhongke Runda's lab.

The operator of the lab that was questioned has asked the Covid-19 testing institution to conduct self-inspection and cooperate with authorities' investigations, the unit of Runda Medical said in a statement today. "The firm will timely perform its obligations for information disclosure if necessary," it added.

The municipal health commission has begun investigating the testing center and will punish it severely if any violations are found, Zhao Dandan, deputy director of the commission, said yesterday.

Yicai Global today saw a statement submitted to authorities on May 9 regarding Zhongke Runda's tests. In the statement, the medical company explained how five positive tests were collected but the samples were different from those mentioned in Yicai Global's report yesterday.

Formed in 2017, Zhongke Runda has three Covid-19 testing centers in Shanghai. It was one of the eastern city's first third-party labs that were approved to conduct testing for Covid-19 in March 2020, according to the statement. It has tested nearly eight million tubes of samples in Shanghai since March 12.

Editor: Emmi Laine, Xiao Yi