SYDNEY (BLOOMBERG) - Singapore Airlines raised its stake in Virgin Australia Holdings Ltd a week after future ownership of the A$1.3 billion airline was put in doubt.

The Singapore carrier increased the shareholding to 23.11 per cent from 22.91 per cent, it said in a statement late on Wednesday (April 6). The airline said it paid A$3.18 million to settle a series of equity swaps, or 46.7 Australian cents on average for each Virgin Australia share.

Speculation about Virgin Australia's ownership mounted last week after the airline's largest shareholder, Air New Zealand Ltd., said it's considering an exit. While the latest purchase barely changes SIA's stake, it's paying 32 per cent more than Virgin Australia's last closing price for the additional shares.

"If one wanted to draw a 'loose' conclusion from last night's announcement, it's that Singapore Air does not seem to have objections to injecting further cash into Virgin," Citigroup's credit trading desk in Sydney said in a note to clients.

Virgin gained 2.1 per cent to 36.25 Australian cents at 1:33 pm in Sydney trading.

SIA has approval from Australia's Foreign Investment Review Board to increase its stake in Virgin Australia to 25.9 per cent. The Singapore carrier declined to comment beyond Wednesday's statement, it said in an e-mail.

Air New Zealand said March 30 it may sell some or all of its 25.89 per cent stake in Brisbane-based Virgin.

Etihad Airways PJSC owns about 24 per cent of Virgin Australia, making it the second-largest shareholder, while Virgin Group owns about 10 per cent, according to data compiled by Bloomberg.

Virgin Australia borrowed A$425 million from its major shareholders last month, giving the airline time to review its balance sheet.