Leaders of flood-stricken Kerala state angrily hit out at India's national government Thursday for rejecting a $100 million aid offer from the United Arab Emirates as more people entered relief camps to escape the devastation.

More than 1.3 million people have now packed into temporary camps even though the floods, which have left at least 420 dead and missing, are fast receding.

The New Delhi government infuriated the Kerala administration by rejecting the cash offer from the wealthy Gulf state.

Kerala's Finance Minister Thomas Isaac accused Prime Minister Narendra Modi's government of adopting a "dog-in-the-manger" policy by refusing the money.

The communist minister added in a Twitter attack that if the right wing national government takes a "negative stance" on the UAE offer "they should compensate Kerala".

Kerala chief minister Pinarayi Vijayan called for "high level" talks with the national government on the dispute.

There are an estimated three million Indians in the UAE, with many from Kerala which has a large Muslim population.

India's foreign ministry announced late Wednesday, however, that the government would stick to its policy of "meeting the requirements for relief and rehabilitation through domestic efforts" and not accept money from foreign governments.

It added that outside money could only be donated through Indian-origin individuals or foundations.

India has a record of refusing foreign aid after disasters, turning down foreign help after the 2004 tsunami, which killed thousands in India. Experts said Indian governments want to prove they can handle any emergency themselves.

The UAE offer was higher than the $97 million so far given by the central government to handle the floods which state authorities estimate have caused damage worth more than $3 billion.

They say 10,000 kilometres (6,000 miles) of roads have been destroyed or damaged, while estimates of the number of houses to be rebuilt vary from 20,000 to 50,000.

Many of the new arrivals in relief camps are people who have returned to their homes to find them uninhabitable.

One 68-year-old man committed suicide on Wednesday after seeing the state of his home at Kothad in Ernakulam district. A 19-year-old boy took his own life earlier this week because his school certificates were destroyed by the floods, police said.

Vijayan said there were now 1.34 million people in 3,300 relief camps, up 300,000 in two days.

In another sign of the extent of the chaos, the reopening of Kochi international airport, the state's main airport, has been put back three days to August 29.

However Tom Jose, the state's top civil servant, told AFP the situation across the state had improved with only isolated pockets of water remaining.

"If it does not rain in the coming days then we can start getting back on track soon," he told AFP after an aerial tour of flood-ravaged areas.

"Rescue operations are almost complete. Our priority now is to provide relief and rebuild the damaged infrastructure," he added.