India's Prime Minister Manmohan Singh has announced five billion rupees (about $108m) of relief aid for flood-hit areas of Tamil Nadu state.
Tamil Nadu has seen very heavy rains this monsoon season
A federal team has also been sent to assess flood damage in 15 districts of the state, an official statement said.
More than 20 people were feared drowned when a boat capsized off the Tamil Nadu coast on Sunday, some 600km (375 miles) from the state capital, Madras.
Two buses were swept away on Friday. At least 77 bodies have so far been found.
Rescuers have so far recovered six bodies, five of them belonging to children, from the vessel which capsized in the sea near Tuticorin on Sunday.
Three people rescued have been taken to hospital. About 40 people are believed to have been on board the boat.
On Friday, one passenger bus was swept away in Thanjavur district, claiming at least 50 lives.
In another incident near Rameswaram on the coast, rescuers recovered the bodies of at least 27 people travelling on a bus from Tiruchchirappalli.
Tamil Nadu has received unusually heavy rains since the third week of October. The most recent heavy spell started a few days ago, hitting southern regions hardest.