Prime Minister Narendra Modi has spoken to chief ministers of both Andhra Pradesh and Telangana to assure Central assistance after unprecedented rainfall in the region.

"Spoke to Telangana CM KCR Garu and AP CM YS Jagan Mohan Reddy Garu regarding the situation in Telangana and AP respectively due to heavy rainfall. Assured all possible support and assistance from the Centre in rescue & relief work," tweeted PM Modi.

The PM said his thoughts are with those affected due to the heavy rains.

The rainfall received by Hyderabad on Tuesday was an all-time high, the met office said on Wednesday.

The 19.2 cm rainfall in the city broke all previous records. The previous highest was 9.83 cm recorded on October 10, 2013, said Dr K. Naga Ratna, scientist at the Hyderabad Meteorological Centre.

Authorities on Wednesday opened 13 of the 17 gates of Himayat Sagar reservoir on the outskirts of Hyderabad to let excess water into the Musi river which flows through the city.

Water entered into houses in several areas on the banks of the river, especially at Chaderghat and Moosarambagh.

Residents in inundated areas were waiting for help. The Moosarambagh causeway across the river was washed away in flood waters.