Crop-nourishing monsoon rains lashed the Kerala coast of India's southwest on Tuesday, the India Meteorological Department said, the earliest start to the rains since 2011 which should boost the world's fasting growing economy's agriculture.

The monsoon delivers about 70 percent of India's annual rainfall, critical for the farm sector that accounts for about 15 percent of India's $2 trillion economy and employs more than half of the country's 1.3 billion people.

India's 260 million farmers depend on monsoon rains to grow crops such as rice, cane, corn, cotton and soybeans because nearly half of the country's farmland lacks irrigation. Higher farm incomes following plentiful rains lift the demand for an array of consumer goods ranging from lipsticks to refrigerators.

Monsoon rains hit the Kerala coast in line with the forecast of the India Meteorological Department, a senior weather department official, who did not wish to be named as she is not authorised to talk to media, said.

The India Meteorological Department declares the arrival of monsoon rains only after parameters measuring the consistency of the rainfall over a defined geography, the intensity, cloudiness and wind speed are satisfied.

Andaman and Nicobar, islands off India's southeastern coast that are usually the first areas to receive the monsoon, received rainfall six days ahead of schedule earlier this month.

The weather office on April 18 forecast this year's monsoon rains at 96 percent of a 50-year average of 89 cm.

As the monsoon intensifies over India, other neighbouring regions have been hit by the separate Cyclone Mora. The storm has caused deaths, destroyed refugee camps and damaged properties across Sri Lanka, Bangladesh and parts of northeastern India.

Landslides and floods in Sri Lanka killed at least 151 people and over 100 people are missing

Bangladesh has evacuated at least 350,000 people as the cyclone lashed coastal areas on Tuesday, officials said, causing havoc in refugee camps set up for Rohingya Muslims who have fled violence in neighbouring Myanmar.

Heavy rains also lashed India's remote northeastern states of Tripura, Mizoram, Manipur, Nagaland and Arunachal Pradesh as Mora moved further up the Bay of Bengal.

However, the cyclone is independent to India's southwest monsoon pattern.

In May, K.J. Ramesh, director general of the Meteorological Department, told Reuters that the country looked likely to receive higher monsoon rainfall than previously forecast as concern over the El Nino weather condition had eased.

El Nino, a warming of ocean surface temperatures in the eastern and central Pacific that typically occurs every few years and was linked to crop damage, fires and flash floods, faded in 2016.