The Union Home ministry has ordered a Central Bureau of Investigation (CBI) inquiry into the supply of substandard medicines in Delhi government hospitals and whether the drugs were also distributed through mohalla clinics, sources said on Friday.

The CBI probe was ordered following a recommendation by Delhi Lt Governor V K Saxena on the matter in December last year.

Saxena said the drugs allegedly "failed quality standard tests" and had the "potential of endangering lives" in hospitals run by Delhi government.

The Delhi government's Directorate of Vigilance had written to the home ministry requesting the probe.

"It also needs to be investigated whether the same drugs which have been procured by the Central Procurement Agency (CPA) are also being distributed to the patients through the 'Mohalla Clinics' or not," the communication read.

The letter said any action for supplying 'Not of Standard Quality' drugs should not be confined to the CPA and there is need to investigate the entire supply chain -- the role of the suppliers who procured from manufacturers and provided supply to the end users, that is, hospitals (patients).

"Besides, there is a need to lift the corporate veil to understand the gravity and motives of supplying 'Not of Standard Quality' drugs," read the Directorate of Vigilance letter.

The drugs that were found to be of "substandard quality" included critical life-saving antibiotics used for the treatment of lung and urinary tract infections such as Cephalexin, according to officials.

The list also included a steroid, Dexamethasone, used for curing life-threatening inflammation in the lungs and joints and swelling in the body, anti-epilepsy and anti-anxiety psychiatric drug Levetiracetam and anti-hypertension drug Amlodepin, the officials said.

"In this context, it is not out of place to mention that the matter of 'Mohalla Clinics' was already entrusted to the CBI and a Preliminary Enquiry (PE) was also registered... ," the communication read.

According to a vigilance department report submitted to the lieutenant governor, of the 43 samples of drugs sent to government laboratories, three failed the test and 12 reports were pending. Further, out of another 43 samples sent to private laboratories, five failed.

Drugs such as Amlodipine, Levetiracetam and Pantoprazole failed the test in both government and private laboratories. Cephalexin and Dexamethasone failed the test in private laboratories.

Delhi Health Minister Saurabh Bharadwaj had demanded action against the city's health secretary in connection with the matter.