COST to insurers from the August 12 Tianjin harbour chemical explosions is expected to exceed US$3 billion, Reuters reports.

While Chinese insurers are likely to bear the brunt, global insurers and reinsurers are expected to set aside reserves to cover the payouts.

Zurich Insurance said last week a $275 million loss from Tianjin was partly responsible for the decision to pull the plug on its GBP5.6 billion (US$8.5 billion) bid for rival RSA.

Reinsurance broker Guy Carpenter has said so-called insured losses from the blasts could be as much as $3.3 billion.

This was based on satellite images of how buildings, cargo, containers and property was hit, but did not cover clean up or contamination costs.

"Marine surveyors appointed by clients say containerised goods have tainted smells," Nick Derrick, chairman of the International Union of Marine Insurance's cargo committee.

He said the impact of dangerous chemicals would add to the final loss figure when contaminated food and drugs are factored in.

One reinsurer also said chemicals were likely to corrode cars outside the immediate blast area. Another said contamination damage could extend to more insurance classes, such as aviation.

Insured losses from the blasts are not, however, expected to reach the $11 billion linked to floods in Thailand in 2011. But insurance specialists said it could be several months before the full extent of the Tianjin losses are known.