The directive is part of instructions to dealers of ammonium nitrate, which has been widely used by terrorists to make explosives, asking them to seek licence from police, a senior police official said.
"All laboratories, educational institutions, medical institutions, hospitals and clinics can possess less than five kg of ammonium nitrate for scientific and educational purposes.
"However, the SHO of the local police station must be informed about the quantity of possession," the official said.
Delhi Police has issued directive to dealers, transporters and users of ammonium nitrate to obtain licence.
The last date to apply for the licence in the capital is May 31, the official said.
"If anyone sells ammonium nitrate after the deadline without a licence, he or she will be liable for prosecution," he said.