Australians who waited months to escape India as coronavirus spread through the country say they lost a place on a repatriation flight provided by their government due to faulty Covid-19 testing.

CRL Diagnostics, which performed the tests for Australian airline Qantas, denied the results were inaccurate, but its managing director said the lab had carried out work while its Indian accreditation was suspended. According to India’s National Accreditation Board for Testing and Calibration Laboratories (NABL), the Delhi-based company’s accreditation was suspended on April 6. Ravi Tomar, managing director of CRL Diagnostics, said the company appealed the three-month suspension, and asked if “during this time should we continue testing or stop but we did not get a reply. So, we continued testing,” he said.

In a statement to CNN, NABL chief executive officer N. Venkateswaran said CRL Diagnostics’ accreditation was suspending for “non-compliance with accreditation norms.” “NABL accreditation is voluntary, and we cannot instruct the lab not to do testing. The suspensions means that they cannot use the NABL symbol or claim accreditation status,” Venkateswaran said. As many as 10 passengers who were blocked from the repatriation flight have since tested negative for Covid-19, according to Sunny Joura, who was barred from the repatriation flight after testing positive. His elderly mother, Darshan, tested negative but could not board the flight as she was a close contact. “I was extremely disappointed and shocked,” Joura said. “My mother and I did not venture out of the house at all for 14 days prior to the pre-flight quarantine. We were double-masking all that time.” Joura took another test soon after with a different provider — it was also negative. Yogesh Hasija, who is in Melbourne, tells a similar story about his wife Preeti Sabharwal, who was booked on the repatriation flight. She tested positive and was bumped from the flight, only to test negative days later.