KOLKATA, May - A cyclone intensified over the Bay of Bengal on Wednesday, forcing a oilfield to shut and cut its gas output, and the evacuation of some 50,000 people in the region, officials said.

Officials also voiced concerns the cyclone, with wind gusts of up to 155 kph (100 mph), could slow the progress of the monsoon rains, vital for India's trillion-dollar economy.

Tropical Cyclone Laila was set to hammer the coast of Andhra Pradesh on Thursday, prompting Reliance Industries to stop oil production and reduce gas output from the region by 10 percent, company sources said.

"We are monitoring the situation and if we find that the cyclone will directly hit our facilities, then our FPSO (Floating Production Storage and Offloading facility) may have to be taken to a safer location," said a company source, who declined to be named as he is not authorised to speak to the media.

The cyclone is forecast to move towards Orissa after striking Andhra Pradesh, but it is likely to weaken by the time it reaches the Paradip port, a hub for iron ore exports.

G.K. Biswal, deputy conservator of Paradip port, said port authorities were on alert although they did not expect any disruption.

CONCERNS FOR MONSOON

Last year some forecasters blamed a cyclone in May for the failure of monsoon rains, but scientists are divided about the impact of tropical storms on the monsoon.

The country has been hit by street protests due to steep food prices, partly the result of last year's poor monsoon rains.

"We have to observe the post-Laila scenario," said Ajit Tyagi, the director general of the Meteorology Department.

Tyagi said the weather office was standing by its forecast last month, which said the June-September monsoon rains would be 98 percent of average.

Monsoon rains reached Andaman and Nicobar islands and several parts of the Bay of Bengal on Monday, three days ahead of schedule.

"Conditions are favourable for further advance of southwest monsoon," the weather office said in its latest five-day forecast.

Local officials said heavy rainfall would help the rice crop that will be sown next month as rains would boost soil moisture and facilitate ploughing.

"Due to pre-monsoon rains, summer planning has started. If the state receives rain, the ploughing will further pick up," said Babaji Giri, director of the agriculture department in the eastern state of Orissa.

Officials in Bangladesh said they had also alerted ports and fishing vessels.