Here are the latest developments in this big story:
Ten people died in Assam on Sunday due to the floods. Six of the deaths took place in Kokrajhar district alone.
Floods have hit 21 of Assam's 22 districts. Altogether, 2,734 villages have been affected in Assam. The worst-affected districts include Dhubri, Kokrajhar and Morigaon.
Nearly 2 lakh people across the state have been accommodated in nearly 600 relief camps.
Three columns of Army and one unit of National Disaster Response Force or NDRF have been pressed into service in Assam since the past three days.
Brahmaputra is overflowing at several places including state capital Guwahati. Ten other rivers are flowing above the danger level.
In Bihar, floods have hit four districts, affecting lakhs of people. Chief Minister NItish Kumar said heavy rains in the upper reaches of Nepal have led to rising water levels in Tapti and Mahananda rivers, which has flooded the northeastern part of the state.
Union Home Minister Rajnath Singh spoke to Mr Kumar on Sunday and discussed the flood situation in the state where nearly 320 NDRF personnel have been rushed.
"The Centre is rushing additional NDRF teams to Bihar to help the ongoing rescue &relief operations in the flood affected region of the state," the home minister tweeted.
Seven teams of NDRF, comprising 45 personnel in each, have already reached the affected areas in Bihar, reported news agency Press Trust of India quoting home ministry sources.
Very heavy rains occurred at most places in Jalpaiguri, Cooch Behar, Alipurduar, Darjeeling and Kalimpong districts of Bengal. The rains have also disrupted train services in north Bengal.
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