On December 11, 2015, one of the regional offices of RBI disclosed that it had received some banknotes of Rs 1,000 denominations with inset letter 'L' belonging to some particular series without the security thread, Sinha said in a written reply in the Rajya Sabha.
The incident happened in the Hosangabad unit of the Security Printing and Minting Corporation of India (SPMCIL).
However, the minister said other essential features were present in the banknotes in question.
"The government has taken these incidents very seriously and has instructed SPMCIL to initiate disciplinary proceedings against the officials involved," Sinha said.
Action has been taken to strengthen quality procedure and initiate online inspection system in the manufacturing process.
"Additional inspections have been introduced to ensure defect-free production," he added.
