PARIS, July 18 (Reuters) - French utility EDF cut output at two reactors at its Tricastin nuclear plant in southern France on Tuesday, due to scorching temperatures, to reduce the amount of heated water from the reactors’ cooling system flowing into the Rhone river.

The Tricastin plant has four pressurised water reactors with an installed capacity of 915 megawatts (MW) each. EDF said on its website that output at reactors 1 and 3 was reduced by 735 MW and 651 MW respectively.

It said this was done for “environmental issues,” without giving further details.

A company spokeswoman said that, due to a heatwave in France on Tuesday, the company decided to reduce the amount of heated non-radioactive water from the cooling systems that flows into a canal near the plant and into the Rhone river.

“This was done so as not to increase the temperature of the already heated water and thus preserve plant and animal life,” she said, adding that a heavy thunderstorm forecast for the area later on Tuesday was expected to cool the situation.

EDF said it expected output at the reactors to return to normal on Wednesday.

France has recorded scorching temperatures in the past couple of days, with the mercury in some areas in the south and southeastern France hitting 38 degrees Celsius (100 degrees Fahrenheit), according to Meteo France.

Available nuclear power, which provides over 75 percent of France’s electricity needs, rose above 70 percent of capacity on Tuesday afternoon from 68 percent previously as the restart of EDF’s 1,300 MW St Alban 1 reactor was ramped up. (Reporting by Bate Felix; Editing by Adrian Croft)