Nearly a hundred people have been killed and around 200,000 displaced by severe flooding in western India in the past week, officials said on Friday.

Hundreds of people waited for help on rooftops and atop a train as authorities in Gujarat state pressed the army into service to help move people to higher ground.

"My home has been swept away and my cattle have perished. The water level has risen overnight and we are moving around in boats," said Pratap Maisuriya of Punjapadar village in Amreli district, one of the worst hit regions.

Weather officials said heavy monsoon rains would continue in the state for the next few days.

"Due to the situation we have sought urgent assistance from the central (federal) government as the situation is very grim," said state minister Kaushik Patel, adding 94 people had died due to the flooding in the past week.

Flooding is common during India's June-September monsoon season but it mostly occurs in northern and eastern India where large rivers such as the Ganges and Brahmaputra flow.