Sony said today shortages of parts and materials would force it to reduce or suspend production at five additional plants in Japan following the catastrophic earthquake this month.

The plants, mostly in central and southern Japan, make products from digital cameras and video cameras to televisions and microphones, the company said in a statement.

Production at the plants will be reduced or temporarily suspended between March 22 and March 31, Sony said.

A sixth plant in Chiba, north of Tokyo, was set to resume production today, but it could be interrupted by the rolling blackouts that are affecting some areas supplied by Tokyo Electric Power (TEPCO).

Production at six northern Japanese Sony plants has been suspended since the disaster and the consumer electronics giant said it was inspecting and repairing buildings and machinery with a view to re-starting production at these sites.

"If the shortage of parts and materials supplied to these plants continues, we will consider necessary measures, including a temporary shift of production overseas," Sony said.

Production was continuing as normal at other factories, but the company said it was keeping a close eye on its supply chain.