NEW DELHI: The ministers who attended the Cabinet meeting on Tuesday evening had to stay back till PM Narendra Modi 's televised address to the nation was over, in order to ensure that there was no premature leak, even by a few minutes, of the plan to scrap Rs 500 and Rs 1,000 notes.The demonetisation plan , the best kept secret in the power corridors of the national capital, was a tightly policed affair with only a handful of top officials privy to the move. Apart from ministers at the Cabinet meeting who had to remain in quarantine for a while, members of the Reserve Bank of India (RBI) board too left only after Modi 's speech.Sources said the official agenda for the Cabinet meeting on Tuesday was a deceptive string of MoUs between India and Japan, and even ministers were not aware about the proposal to ban high value currency notes."We just got some indication 10 minutes before the meeting started. It was a bold step by government. All ministers remained in the meeting hall from 6.45pm to 9pm until the PM's address to the nation ended," a minister said.The Cabinet meeting ended around 7.30pm and the PM went to meet the President to inform him about the decision. "All ministers remained in the meeting hall.The PM held another meeting with three senior ministers later, which went on till late night," a source said.It's worth mentioning that only a few weeks ago, the cabinet secretariat had issued a circular, to personal staff of all ministers, advising ministers not to carry mobile phones to the Cabinet meeting . "So, there was no scope of the information going out," said a source.The government had also planned the timing of the Cabinet meeting. It was moved to the late evening slot and the RBI board also met around the same time. Sources said this was done to ensure that the news did not leak out.