Six workers were killed and 15 others injured when an elevated section of the Delhi Metro track under construction at Zamrudpur in south Delhi collapsed early Sunday morning. The next day, six people were injured at the same spot when three cranes, being used to remove a steel girder that had got inclined, suddenly toppled over.

According to the audit report, the Delhi Metro needed to evolve a mechanism for testing all materials through accredited laboratories. It said accountability issues should not be placed at unreasonable risk in the interests of expediency.

'Audit analysis of quality control indicated scaling down of testing requirements, non-witnessing of tests by the company's representatives, testing of material in non-accredited laboratories and non-preservation of test reports,' the report said.

'The company has not prepared a corporate plan to chart out its goals and strategies for achievement of business development, diversification, technology upgradation, and customer satisfaction.'