Zurich Insurance Group Ltd. on Monday said it has pulled out of discussions to buy London-based rival RSA Insurance Group P.L.C., citing uncertainty over Zurich's claims from the August Chinese port explosions among other factors.

Zurich had a Sept. 22 deadline to make a formal bid for RSA.

Zurich said in a statement that the recent deterioration in certain parts of its nonlife insurance book, coupled with uncertainty over claims related to the explosions in the Chinese port of Tianjin last month likely will result in its nonlife insurance business reporting an operating loss of about $200 million for the third quarter of 2015.

The Swiss multiline insurer said it currently estimated losses from the series of explosions at Tianjin of about $275 million, but noted that there was still considerable uncertainty about the nature of many of the losses and costs related to an extended remediation period to complete repairs.

“In addition to claims relating to the Tianjin port explosions, Zurich now expects that weaker-than-expected profitability in the general insurance business in the first half of 2015 will continue in the third quarter,” the company said in the statement.

It added that Kristof Terryn, who will take up the role of CEO of general insurance on Oct. 1, following the resignation of Mike Kerner for personal reasons, is “conducting an in-depth review of the business.”

Zurich said that, in the light of the recent deterioration in the performance of its nonlife insurance operations, it had decided to terminate discussions with RSA and focus instead on “taking the necessary actions to deliver on the required performance of the general insurance business.”

RSA said Monday in a statement that, since the unsolicited approach by Zurich in late July, it had “continued to make good progress” on its action plans, adding that trading result for July and August had been ahead of expectations.

“Zurich has confirmed to RSA that the due diligence findings were in line with their expectations and, while the process had not been finally concluded, they had not found anything that would have prevented them from proceeding with the transaction on the terms announced on Aug. 25, 2015,” RSA said in the statement.

Zurich will report its third-quarter results on Nov. 5.

RSA also will release an interim management statement on Nov. 5.