Japan's devastating earthquake and tsunami in March are set to make 2011 the costliest year on record for natural disasters, German insurance giant Munich Re said on Tuesday.

Total economic losses for the first six months alone were $265 billion, easily exceeding the $220 billion recorded for the whole of 2005, previously the most expensive year to date, Munich Re said.

The total loss amount was more than five times higher than the average of the past 10 years. Losses to insurance firms were some $60 billion, nearly five times the average since 2001.

The 9.0-magnitude quake on March 11, the strongest ever registered in Japan, caused losses of 210 billion euros and killed 15,500 people, making it the costliest natural catastrophe on record.

"It is very rare for such an extreme accumulation of natural hazard events to be encountered as in the first half-year," Munich Re, the world's top reinsurer, said in a statement.

First-half losses are generally lower than second-half losses, which are often affected by hurricanes in the North Atlantic and typhoons in the Northwest Pacific, it added.

The total number of loss-relevant natural events in the first six months of 2011 was 355, somewhat below the average for the previous 10 years of 390.

The next costliest natural disaster in the first half of 2011 was a severe earthquake that shook Christchurch, New Zealand, in February, causing $20 billion in losses, Munich Re said.