NEW DELHI Supplies of drinking water in the Indian capital will fall by a quarter on Thursday and Friday because three treatment plants have been flooded, the city government said, as the Yamuna river overflowed after incessant rain.

Delhi's river is at its highest level in 45 years after unusually heavy downpours in neighbouring states like Haryana, to the north.

The city of 20 million people also saw heavy rain over the weekend with flooding in low-lying communities that forced hundreds of people to seek shelter in relief camps.

"There will be a water problem in some areas of Delhi," the city's chief minister, Arvind Kejriwal, said on Twitter.

"As soon as the Yamuna water recedes, we will try to start them as soon as possible," he said of the three water treatment plants.

Kejriwal said the water level in the river could peak later on Thursday and in the meantime, people were being evacuated from flooded areas.

"Saving the lives of people is most important. I appeal to all the people of Delhi to cooperate with each other in every possible way in this emergency," he told reporters.

North Indian states near Delhi had received record rainfall since the monsoon began on June 1, with Punjab and Himachal Pradesh recording 100% and 70% more rain than average, respectively, the India Meteorological Department said.

Delhi too has recorded 112% above-average rainfall, the department said.

Flood barriers have been set up in the posh Civil Lines residential area, where some top officials live, including Kejriwal, live in a bid to block the surging river water.

(Reporting by Krishna N. Das; editing by Robert Birsel)