The Centre declared one-day state mourning on Tuesday in view of the demise of Tamil Nadu Chief Minister J Jayalalithaa.
A Home Ministry spokesperson said the national flag on all government buildings across the country will be flown at half-mast throughout the day.
The central government will also accord a state funeral to Jayalalithaa.
Jayalalithaa, a popular leader who showered the poor with populist programmes, died last night at a private hospital in Chennai after battling for life for 75 days.
The 67-year-old politics leader had suffered a massive cardiac arrest on Sunday evening.