New Delhi, Sep 10 - In a major step to retain the heritage of the Edwin Lutyens- designed North and South Blocks in the heart of the capital, the government Thursday laid down guidelines for carrying out repairs on the imposing secretariat buildings.

'Buildings of North and South Block are valuable heritage structures and need to be conserved in their original form and shape to the extent possible,' Information and Broadcasting Minister Ambika Soni said, adding that the cabinet had decided that henceforth, repairs of the two buildings would be conducted after approval by a special committee set up for the purpose.

'The cabinet approved that, in future, all addition-alteration work including repair work involving changes in the original specifications of these buildings will be carried out only after consulting the Special Advisory Committee on Conservation and Protection of North/South Block constituted for the purpose,' she said.

Soni was briefing reporters after a cabinet meeting presided over by Prime Minister Manmohan Singh.

The North and South Blocks flank Rajpath, the imposing boulevard that begins from the Rashtrapati Bhawan presidential palace and runs three km to the India Gate war memorial to the unknown soldier.

South Block, which lies to the right of Rashtrapati Bhawan, is home to the Prime Minister's Office (PMO) and the ministries of defence and external affairs.