An official statement from the Prime Minister's Office said Modi spoke with Vijayan again on Thursday morning.

"We discussed the flood situation in the state. Have asked Defence Ministry to further step up the rescue and relief operations across the state. Praying for the safety and well-being of the people of Kerala," the Prime Minister said.

Incessant rains have led to massive flooding across Kerala. Twelve deaths were reported on Thursday, taking the toll to 79 since August 8. More rain was forecast till Saturday.

The state has been on a red alert since Wednesday evening when 28 people were killed in the flooding.

Pathanamthitta district in central Kerala has been the worst affected since Wednesday as thousands of people -- students among others -- were trapped in their homes in Ranni, Aranmula and Kozhencherry.

The Army, responding to the emergency situation, constructed a footbridge at Padikkad from local resources on Wednesday evening. A column of the 44 Field Regiment constructed the 35-feet footbridge at Padikkad despite the rain not stopping.

Soldiers have rescued nearly 100 persons, including children and senior citizens, from Malampuzha's Valiyakadu village.

Personnel from the National Disaster Response Force (NDRF) evacuated over 900 persons to safer places at Pathamithitta, Kozzhikode, Ernakulam, Thrissur and Alappuzha.

The central government said it has launched massive rescue and relief operations in Kerala.

Cabinet Secretary P.K. Sinha chaired a high level meeting on the Prime Minister's instructions here and asked the Army, Navy, Air Force, Coast Guard and the NDRF to mobilise additional manpower, boats and helicopters to scale up the relief measures in Kerala.

An official spokesperson said food packets and drinking water were rushed to the state.

A navy spokesperson said the Southern Naval Command has suspended all routine training activities and shifted its focus to the highest state of readiness in the wake of the situation in Kerala.

The spokesperson said all available resources for rescue and relief efforts in Ernakulam and Trichur have been mobilised.