Out of the total 19 projects, the highest number were done by PWD (six), followed by Municipal Corporation of Delhi (four), New Delhi Municipal Council and Central Public Works Department (three each), Delhi Development Authority (two) and RITES (one).

"The observations were communicated to the respective executing departments for clarification, remedial measures, fixing responsibilities etc," Minister of State for Personnel, Public Grievances and Pensions V Narayanasamy told Lok Sabha in a written reply to a question.

Further, six cases have been registered by the CBI, the minister said.

"During intensive examination, samples of cement/concrete taken from the works of flyovers at Naraina, Barapulla and Gazipur failed to meet the contract standards.

"The executing departments have been advised by the CVC to carry out further conformity tests like load test etc. to confirm the safety of structures and quality of concrete," Narayanasamy said.

"A case has also been registered by the CBI pertaining to Barapullah Elevated Flyover," he said.