The Humanitarian Director of Save the Children Ray Kancharla said Kerala had not experienced such a big disaster and the recovery process would require a lot of work, investment, and resources.
Dozens of boats including 51 navy vessels are involved in the evacuation.
Chief Minister Vijayan has estimated that more than two million people have been forced to move into relief camps since the monsoon season brought torrential rains three months ago.
It has been nine days since the rains began and about 164 people have lost their lives with about 2.25 lakh people in relief camps.
The president of the UAE, Khalifa bin Zayed Al Nahyan, has expressed his condolences to Prime Minister Narendra Modi on the loss and damage in the Kerala floods.
Following the cancellation, Modi chaired a meeting with Governor P Sathasivam, Chief Minister Pinarayi Vijayan and other officials and witnessed a video presentation of the widespread destruction across the state.More news: Stormy Daniels explains Celebrity Big Brother exit
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The Prime Minister visited Kerala to review the situation arising out of floods in the State.
During the current monsoon, Kerala has been hit with over a third more rain than average, according to India's weather office.
Helicopters have also been dropping emergency food and water supplies, while special trains carrying drinking water have been sent to Kerala.
While more than 58,000 people were rescued in districts like Ernakulam, Chengannur, Pathanamthitta and Thrissur, there are still many more waiting to be rescued. Many people are still stranded as they prefer to be in their homes.
The government says 10,000 kilometres (6,000 miles) of Kerala roads have been destroyed or damaged, along with thousands of homes.
The airport in the main commercial city of Kochi has been flooded and operations suspended until August 26 with flights being diverted to two other airports in the state.
The gates of dozens of dams and reservoirs across the state have been opened as water levels reach unsafe levels, inundating many other villages. A total of 407 people have died in Kerala, 190 in Uttar Pradesh, 183 people in West Bengal, 139 in Maharashtra, 52 in Gujarat, 45 in Assam and 11 in Nagaland state, officials and the Press Trust of India news agency reported.