"I have received a report that our air defense radar system in Sabang is strong and it did not detect an airplane (flying over the Indonesian territory)," Purnomo said here on Wednesday.
The military radar owned by the Defense Ministry is more sensitive than civil radar and, thus, there is no reason to doubt its accuracy, he noted.
He said if an airplane flies to the north of Malaysia and the south of Thailand the Indonesian radar will not be able to detect it.
"The military radar is under our control," he said.
Purnomo noted that his Malaysian counterpart contacted him on Wednesday morning to ask for help in the search for the missing MH370 Malaysian Airline.
"(The Malaysian defense minister) telephoned me this morning to ask for Indonesia's help as the deadline to find the black box is 20 days away," he remarked.
He said he had informed President Susilo Yudhoyono of Malaysia's request. The President discussed the request at a cabinet meeting here on Wednesday evening.
Indonesia has committed itself to help its neighbor find the airplane, he said.
The flight MH370 was carrying 227 passengers, including seven Indonesians on board, plus two pilots and 11 cabin attendants, when it lost contact with the Subang Air Traffic Control early on Saturday morning, March 8.
The Boeing B-777-200ER aircraft left Kuala Lumpur for Beijing at 12.21 a.m.