Calcutta, April 25: Large areas of the city and most of Bengal experienced prolonged power cuts this evening as the shortfall in the CESC and state electricity board-served areas shot up to about 470 mw.

Officials in the power department said the situation is expected to improve only marginally tomorrow when a standby unit at Kolaghat plant is expected to be started. But there will not be respite from power cuts this week.

The deficit in Calcutta and its adjoining areas supplied by the private power utility, CESC, shot up to 150 mw this evening. The situation was worse in areas in the rest of Bengal served by the state electricity board, as the shortfall soared to around 320 mw.

CESC sought about 340 mw from the state electricity board grid but was allowed to draw only 170 mw.

The power department had earlier predicted that power cuts would plague Bengal this summer because of a 250-mw increase in demand than last year. Arrangements had also been made by the state electricity board to take about 200 mw from the Damodar Valley Corporation (DVC).

Officials said the crisis began to take shape late last week after two 200-mw units were shut down at the National Thermal Power Corporation (NTPC) unit at Farakka because of scarcity of water. This led to a sharp drop in supply to the state electricity board.

A 500-mw NTPC unit at Talcher has also been shut down for repairs.

In addition, DVC, which had agreed to supply 200 mw daily to the state board grid during April, has failed to do so. It has been supplying about 25 mw since Saturday.

Power minister Mrinal Banerjee said: ?The situation is grim despite good generation by our plants. We are contacting the Union power ministry and trying to fetch power from other sources.?

Power department officials said the pinch was not felt over the weekend as most offices and establishments were closed.

?But the deficit was felt today,? said an official.

?Today, five 210-mw units at the Kolaghat plant generated about 950 mw. We will step up the generation by nearly another 200 mw tomorrow,? said S. Mahapatra, managing director of Power Development Corporation Limited.

Two units at Santaldih, which were shut down for repairs, have also been started to tide over the crisis.