(Updates with further details and background throughout) Aug 9...

(Updates with further details and background throughout)

Aug 9 (Reuters) - Australia's QBE Insurance (QBE) said on Friday it had entered transactions with Britain-based RiverStone International and global insurance group Enstar ESGR.O in a bid to de-risk the firm's exposure to reserves totalling about $1.6 billion.

The reinsurance deals with the parties will de-risk all of QBE's North America middle-market reserves and a small number of other portfolios in its international and North America businesses.

The reserves transaction will also lead to a $230 million net capital benefit for QBE in the second half of the year.

"Alongside prior reserve transactions, QBE has now protected ~20% of long tail reserves, which have collectively contributed over $1 billion in adverse prior development through recent periods," the firm said in a statement.

The deal will serve to further de-risk long-tail reserves for older accident years, QBE said, adding that it would drive greater capital efficiency for the firm.