The accused have been identified as Esmatullah (40), Khalilullah (22), from Afghanistan and Victor Osondu (37) from Nigeria.

Deputy Commissioner of Police P.S. Kushwah said they are the key members of an international drug cartel.

The three were arrested on Tuesday at 1.15 a.m. from Saket when Esmatullah and Khalilullah came to deliver a consignment of heroin to Osondo, Kushwah said.

"Apart from heroin, Osondo handed $4,200 to Esmatullah. The amount has been seized," the officer said, adding a case has been registered under relevant sections of the Indian Penal Code.

They told the police that they had been involved in the heroin supply in Delhi and adjoining states for the last three years and have sold more than 100 kg in the capital in the last two years.

"Esmatullah and Khalilullah have brought heroin from their country -- sometimes by storing the capsules in their stomach and sometimes in secret cavities of their bags in flights," Kushwah said.

"They brought about 15-kg heroin on August 30, out of which, 5 kg was to be delivered to Osondo, who came to India in 2014 on a six-month business visa, but stayed back even after its expiry," police said.

Osondo told the police that he bought heroin from Esmatullah and Khalilullah to supply to other countries including Canada, UK, France, South Africa through courier companies.