* Late monsoon start to welcome new Indian govt
* Delay not a big issue but El Nino is - farmers' group
* India battling slow economic growth, high inflation (Adds chief forecaster's comments and farmers' group's quote)
By Ratnajyoti Dutta
NEW DELHI, May 15 (Reuters) - India's monsoon may hit the southern Kerala coast around June 5, the weather office said on Thursday, in a likely delayed onset that raises fears of poor rains in the initial days of a monsoon season threatened by the El Nino weather pattern.
A delay in rains for monsoon-dependent India could pose challenges for the country's next government, possibly pushing up inflation and denting economic growth. Results due on Friday are likely to hand opposition leader Narendra Modi a majority.
"We are expecting a slight delay in the monsoon onset than the normal date of arrival," said D.S. Pai, lead forecaster of the Indian government's weather office.
The India Meteorological Department (IMD) treats June 1 as the normal date for the monsoon arrival over the southern coast.
The predicted onset date has an error margin of four days, the IMD said in a statement.
"The countdown for monsoon onset starts from June 2 and in an extreme case it could arrive as late as June 9," Pai told Reuters by telephone from the western city of Pune.
Rains are vital to rejuvenate Asia's third-largest economy as it battles its worst slowdown since the 1980s and attempts to cool inflation that has averaged nearly 10 percent for the past two years.
"A delay of five days is not the big issue but the probability of El Nino is a serious concern for farmers," said Sudhir Panwar, chief of farmers' lobby group Kisan Jagriti Manch.
Agriculture accounts for 14 percent of India's nearly $2 trillion economy, with two-thirds of its 1.2 billion population living in rural areas. Half of the country's farmland lacks access to irrigation.
Poor rains could hit sowing of summer crops such as soybeans, rice, corn and cotton, raising food prices and pressuring economic growth that has nearly halved to below 5 percent in the past two years.
Last month, the IMD forecast a patchy monsoon season with a high chance of El Nino, a weather warming event in the Pacific Ocean associated with droughts in the Asia Pacific, including India.
In 2013 the monsoon hit Kerala on June 1, two days ahead of the forecast by the weather office. The season brought above-average rainfall across the country, resulting in record grains production.
To reduce its dependence on rains, however, India plans to expand irrigated farmland by at least a tenth by 2017.
Modi is set to become India's next prime minister, four major exit polls showed, with his Bharatiya Janata Party (BJP) and its allies forecast to sweep to a parliamentary majority in the world's biggest ever election. (Editing by Douglas Busvine and Muralikumar Anantharaman)