UPDATE 1-Japan June power demand falls 5.3 pct yr/yr

* Year-on-year fall widens from 4.5 pct in May -calculations

* Several utilities ask customers to save on power

(Adds details, table)

TOKYO, July 4 (Reuters) - Japan's power demand fell 5.3
percent in June from a year earlier, Reuters calculations based
on industry data from the Electric Power System Council of Japan
showed on Monday, widening from a 4.5 percent decline in May.

Several utilities have asked consumers to cut back on
electricity use amid concerns over power supplies. Only 19 of
the country's 54 nuclear reactors are operating, leaving the
world's third-largest economy turning to other fuels to plug the
shortfall.

Power demand declined for a fourth straight month, after the
massive earthquake and tsunami on March 11 damaged
infrastructure, disrupted supply chains and tipped the economy
into recession.

The Federation of Electric Power Companies of Japan is due
to release its more closely watched power generation data for
last month on July 12.

Last month, the federation's data showed Japan's 10 regional
power companies had generated 4.7 percent less electricity in
May than a year earlier, slowing from an 8.2 percent decline in
April, which was the steepest year-on-year fall since September
2009.

The Electric Power System Council's daily data covers
Japan's four main islands, dividing them into nine regions, but
does not include the southern islands served by Okinawa Electric
Power Co , the country's smallest power firm.

Instead, the data reflects demand seen by independent power
producers in the same area.

Power demand in areas covered by Tokyo Electric Power Co
(Tepco) fell 11.7 percent in June, according to Reuters
calculations based on the data from the Electric Power System
Council, Japan's sole power grid body.

Demand in Tepco's areas, which normally account for about a
third of total power sales in Japan, fell 8.3 percent in May,
15.3 percent in April and 9.2 percent in March.

Power demand in areas covered by Tohoku Electric Power Co
, the utility most damaged by the magnitude 9.0 quake
and subsequent tsunami, fell 12.5 percent in June, the same as
in May. That compared with declines of 19.1 percent in April and
15.9 percent in March.

Following is a table of June power demand at nine areas
served by the utilities of the same name, and the year-on-year
percentage changes, according to the Reuters calculations.

Area Yr/Yr change

Hokkaido -1.2 pct

Tohoku -12.5 pct

Tokyo -11.7 pct

Chubu -1.9 pct

Hokuriku -0.7 pct

Kansai -0.2 pct

Chugoku -0.8 pct

Shikoku +1.5 pct

Kyushu +1.6 pct

(Reporting by Osamu Tsukimori; Editing by Chris Gallagher)