Hardening its stand on the Quattrocchi issue, the opposition National Democratic Alliance on Thursday demanded that Prime Minister Manmohan Singh explain to Parliament as to why information regarding the detention of the Italian businessman in Argentina was suppressed for days together.

NDA leaders met early in the morning to chalk out their strategy on the government's response to the detention of the Bofors' accused a day after they did not take up the issue in the House to allow smooth presentation of the General Budget.

Senior Bharatiya Janata Party leader Sushma Swaraj said the Opposition has taken serious note of the prime minister's statement on the Quattrocchi issue outside the House. The NDA, she said, believed that either prime minister himself or External Affairs Minister Pranab Mukherjee should respond to the Opposition demand for an explanation over Quattrocchi's detention and subsequent bail.