British insurer Prudential PLC on Wednesday delayed a planned $21 billion rights issue, raising fears about the $35.5 billion takeover of Asia-based life insurer AIA Group.

The insurer had planned to detail on Wednesday the pricing of the cash call and of the acquisition it is intended to fund, but instead said it was continuing discussions with the Financial Services Authority about the terms of the deal, particularly the capital position of the enlarged group.

The announcement, coming amid turmoil in world stock markets, saw Prudential's shares close down 1.7 percent to 549 pence ($8.29) in London.

Prudential said it does not expect the delay to affect the overall timing for the completion of the AIA purchase, which it plans to close during the third quarter of this year.

"We are entirely committed to the transaction and remain on track to complete it within the timing set out on 1 March," said Prudential Chairman Harvey McGrath. "The work completed since 1 March with the AIA and Prudential teams has convinced me more than ever that the enlarged Group will be in a position to capture sustainable and highly profitable growth and will deliver substantial long term value for our shareholders."

American International Group Inc. put AIA up for sale as part of its attempts to restructure, become profitable and repay the U.S. government for a bailout at the height of the 2008 crisis.