The two Afghan nationals -- Mohd Masoom (45) and Mohammed (30) had allegedly brought the contraband, worth about Rs 15 crore in the international market, from Kandahar.
"They had boarded an Ariana Airlines flight from Kabul and landed in Delhi last evening. We had a tip off and we arrested three persons in this connection," Delhi Police Commissioner Y S Dadwal told reporters.
Asked how they managed to dodge airport security, Dadwal said the customs officials at the airport were the best to comment on it. "There are methods to conceal contraband. Some people manage to dodge security," he said.
Initial investigations have suggested that the consignment was sent from Kabul by an alleged Afghan smuggler Dawood, who earlier stayed in Lajpat Nagar.
City Police's Crime Branch caught Mohd Masoom (45), an Afghan national, and Raju Dawar (23), who resides in Lajpat Nagar, from the airport here at around 7:30 pm yesterday soon after the former handed over the heroin to the latter.
Mohammed, the second Afghan national, managed to give police a slip but was later caught from Hotel Kabli in Jankpura in south-east Delhi after investigators got the hotel address from the two others.
"We had a tip off. We were tracking Dawar. He was unobtrusively trailed by police. Dawar was seen proceeding to Gate No 2 of the airport and after sometime he along with Masoom was spotted coming back with a suit case," Dadwal said.
Both of them were intercepted and during searches, 7.1 kg of heroin was allegedly recovered from the a cavity created inside the suitcase. Separately, Masoom was found carrying 500 grams heroin in his jacket.
Their interrogation led to the arrest of Mohammed who had given police a slip. Police recovered 7.4 kg of heroin from Mohammed after a raid in hotel Kabli.
"Mohammed had checked into the hotel to deliver the consignment to one of their customers," Dadwal said.
Their interrogation also revealed that Dawood's son is presently lodged in Amritsar jail for the past one year for allegedly smuggling heroin. Dawood had earlier come to the capital as a refugee from Afghanistan and later returned, he said.
"This is one of the biggest catches of Delhi Police in recent years," Dadwal said.
Police have recovered a car which Dawar drove to the airport and two passports issued in Afghanistan.