SENDAI, Japan—Insured losses from the devastating earthquake and tsunami that hit Japan on Friday could be market-changing, according to a major global reinsurer.

The earthquake's impact on the reinsurance market likely will be felt beyond Japan, said a spokeswoman for Germany's Hannover Re Group. “It will turn the prices in Japan,” she said, “but it seems this earthquake could also have implications on worldwide capacity and spring a market change.”

Hannover Re could not immediately estimate its losses in the quake.

Swiss Reinsurance Co. and Munich Reinsurance Co. also said Friday that their losses would not be estimated until the extent of the devastation could be assessed.

Paul Kneuer, senior vp and chief reinsurance strategist for reinsurance broker Holborn Corp. in New York, said losses from the quake will be “far more than $10 billion” and affect every major reinsurance market. “It will certainly be the biggest loss ever outside of the United States,” Mr. Kneuer said.

“This by itself will not be enough to kind of tap out reinsurers' capital, but every reinsurer is losing money this year,” he said. “Clearly, in some parts of the world where prices have been very low, they will increase,” but the impact on the U.S. market is unclear.

“It's way too early” to estimate damages from the earthquake or to determine whether it is a market-changing event,” said Andrew Chester, managing director at Bowring Marsh Ltd. in London during a telephone media briefing.

“The largest earthquake ever recorded in Japan has caused significant damage across the northeast of the country and Tokyo as well,” Mr. Chester said.

The previous strongest earthquake on record for Japan, according to the U.S. Geological Survey, occurred in 1896 when an 8.5 magnitude quake struck Sanriku, Japan, killing 27,000 and causing an 80-foot tsunami.

Mr. Chester said Japan's earthquake pool is reinsured by the government, with “some reinsurance” purchased on the open market.

Mr. Chester said several London underwriters have decided not to write Japanese business for the time being until more is known about the quake.

He added that the effects of the tsunami spawned by the quake have yet to be known.

Mr. Chester also noted that because of the Chile earthquake, two New Zealand quakes, the Australia floods and now the Japan quake, there is “no doubt at all there's an increasing focus on catastrophe risks and the prices markets are willing to charge for those particular events.”

While it's a “little too soon to tell” exactly what impact the earthquake will have on the global reinsurance market, it will be “probably significant in that catastrophe losses in well-insured countries like Japan tend to be reinsured,” said Robert Hartwig, president of the New York-based Insurance Information Institute. “There will be a very substantial impact on the Japanese domestic property/casualty insurance business, global reinsurance markets, and potentially on the catastrophe bond markets. There certainly is a Japanese earthquake exposure in the cat bond market.”

Mr. Hartwig noted that the quake appears to be the fifth largest since 1900 and will be “clearly a many billion-dollar event.”

Nick Pope, an analyst with Jefferies International Ltd. in London, said the brokerage expects an insured loss of around $10 billion. “There's not a particularly high penetration of earthquake insurance in Japan,” especially among homeowners, he said.

The Kobe earthquake in 1995 caused about $100 billion in economic losses and about $3 billion of the total was covered by insurance, Mr. Pope said.

He said if losses in last week's quake are held to about $10 billion, rates would go up locally for earthquake coverage, but he said he doesn't believe the global market would turn. It would take about $50 billion in insured losses to turn the market, he said, and losses may not reach that level this year—even including claims from the recent New Zealand earthquake.