The amount of global capital available to underwrite reinsurance reached $510 billion in the first half of 2013 — its highest level ever, according to research by Aon Benfield, a unit of Aon P.L.C.

In its Aon Benfield Aggregate Report for the first half of 2013, published Monday, the London-based brokerage said the global capital available to underwrite reinsurance business, including third-party nontraditional capital, increased by 1% from December 2012 to June 2013.

This increase was caused by the overall solid earnings of major insurers and reinsurers as well as a continued influx of new capital, but was somewhat offset by unrealized losses on bond portfolios filtering through, said Mike Van Slooten, London-based head of Aon Benfield's international market analysis team, at a briefing Monday.

The increased amount of capital available makes it a “pretty good time to be a buyer of reinsurance,” as the traditional reinsurance market “is likely to be unusually responsive to your needs” and the nontraditional market can provide fully collateralized coverage, said Mr. Van Slooten.

The Aon Benfield Aggregate Report tracks the results of 31 leading global reinsurers.

The study found that the combined ratio of that group was 89.0% for the first six months of 2013, compared with 90.7% for the first half of 2012.

The gross property/casualty reinsurance premiums written by the group totaled $109 billion for the first half of 2013, compared with $103 billion for the first six months of last year.

Aon Benfield executives noted during the briefing in London that reinsurers seeking growth opportunities are showing increased interest in the reinsurance of government-backed catastrophe pools in many areas across the world.

Dominic Christian, co-CEO of Aon Benfield, said both traditional reinsurers and nontraditional sources of reinsurance capital were showing increased interest in underwriting such risks.

He added that reinsurers also are showing increased willingness to underwrite “composite” or “multiline” reinsurance coverages, which underwrite, for example, both property and marine terrorism risks.