(Bloomberg) ? Munich Re and Swiss Reinsurance Co., the world?s largest reinsurers, may lead an increase in premium rates for catastrophe coverage after Hurricane Katrina caused an estimated $35 billion in insured losses.

Reinsurers, which help insurers shoulder risks in exchange for premium payments, may seek to push up rates when they meet with clients such as Allianz AG in Monte Carlo starting September 11 to begin negotiating 2006 contracts. They?ll convene again in the German town of Baden-Baden in October to complete agreements.

After Katrina, ?reinsurers in Monte Carlo are in a much better position to argue for improvements in premiums,? said Andreas Schaefer, an analyst at WestLB Equity Markets in Frankfurt.

The shares of Munich Re and Swiss Re have gained since Hurricane Katrina stuck the US Gulf Coast on August 29, partly on speculation the losses will enable reinsurers to bolster prices. Katrina dislodged offshore oil rigs, flattened homes, flooded New Orleans, left hundreds dead and brought commerce on the US Gulf Coast to a standstill.

The storm may be the costliest ever, according to estimates from analysts including Risk Management Solutions. UBS AG analysts, in a note to investors on Wednesday, raised Swiss Re shares to `buy? from `neutral,? and said Katrina?s losses are ?likely to slow down or reverse downward pricing in the majority of reinsurance lines.? UBS on Friday raised its price forecast for Munich Re shares to 100 euros ($124) from 95 euros.

Shares of the Munich-based reinsurer rose 0.3 percent to 93.07 euros at 2:14 p.m. in Frankfurt on Friday. Swiss Re, based in Zurich, was little changed at 82.10 francs ($66.05).

Reinsurance prices rose for three years after the September 11, 2001, attacks as companies sought to replenish reserves depleted by claims and falling stock markets. Prices for property coverage jumped by as much as 20 percent in Florida after hurricanes Charlie, Frances, Ivan and Jeanne struck the state in 2004, Fitch Ratings said. The storms caused $22.9 billion in insured losses, according to Insurance Services Office Inc.

Rates in other lines of business, such as aviation and professional liability, have been falling for more than a year.

Overall, reinsurance rates fell 1 percent in January, compared with a 4.5 percent increase the previous year and an 11 percent jump in 2003, according to a report from Fitch this week.