Cuba orders extreme measures to cut energy use

* Cuba's energy situation termed "critical"

* Some factories, workshops to be closed through December

* Most other economic activities to be reduced

By Marc Frank

HAVANA, Nov 11 (Reuters) - Cuba has ordered all state enterprises to adopt "extreme measures" to cut energy usage through the end of the year in hopes of avoiding the dreaded blackouts that plagued the country following the 1991 collapse of its then-top ally, the Soviet Union.

In documents seen by Reuters, government officials have been warned that the island is facing a "critical" energy shortage that requires the closing of non-essential factories and workshops and the shutting down of air conditioners and refrigerators not needed to preserve food and medicine.

Cuba has cut government spending and slashed imports after being hit hard by the global financial crisis and the cost of recovering from three hurricanes that struck last year.

"The energy situation we face is critical and if we do not adopt extreme measures we will have to revert to planned blackouts affecting the population," said a recently circulated message from the Council of Ministers.

"Company directors will analyze the activities that will be stopped and others reduced, leaving only those that guarantee exports, substitution of imports and basic services for the population," according to another distributed by the light industry sector.