The accused was caught last night, they said.
Acting on a tip-off that the ASI, identified as Bhola Singh Yadav, had demanded a bribe of Rs 10 lakh from a scrap dealer to give a clean chit to him in a case related to theft of huge quantity of railway's signal wire, CBI SP Manish Surti told reporters today.
The ASI had arrested a person, identified as Nandlal Soni in this regard, who told police that he had sold the cables to scrap dealer Narayan Aswani, from whom Yadav demanded money.
Aswani then asked Yadav to collect the first instalment of Rs two lakh from his shop, situated in Sindhi camp area and the moment he handed over the money, CBI sleuths waiting nearby caught him red-handed.
The ASI had joined the RPF six months back, Surti said adding that a case under Prevention of Corruption Act has been registered against him and further investigations are on.