India, Sept. 6 -- India's drug regulator has traced a batch of the anti-rabies vaccine Abhayrab, which it flagged as misbranded and not of standard quality after it failed a potency test, to an unlicensed flat in north Delhi from where police seized the vials in April, the Central Drugs Standard Control Organisation said on Saturday.

Four people have been arrested in the case.

The seizure is the second time in less than two years that counterfeit Abhayrab doses have surfaced in India.

The regulator's public notice sets out for the first time where the doses of batch KE25012 came from. On August 27, Drugs Controller General of India Rajeev Singh Raghuvanshi asked state drug controllers to alert their inspectorate staff and maintain stri...