SINGAPORE (Bloomberg) - Singapore Telecommunications' 11 per cent rise in third-quarter profit came on the back of mobile growth at Australian unit Optus and improved earnings at Bharti Airtel Ltd.

Net income increased to $970 million in the quarter ended December from $872 million a year earlier, the company said on Thursday.

Earnings before interest, tax, depreciation and amortization were $1.23 billion, below the $1.25 billion median estimate of three analysts surveyed by Bloomberg News.

Stakes in regional wireless carriers including in Thailand and Indonesia are helping Singtel ride out slowing growth in its home market. Earnings more than doubled last quarter at Bharti Airtel, India's biggest wireless carrier, while Optus took on Telstra Corp.'s dominant Australian position with cheaper mobile data plans, according to Citigroup.

"Optus is getting some momentum in post-paid mobile subscriber numbers," Daniel Mueller, an analyst at Morningstar Inc. in Sydney, said by phone before the results. "'They're in a very dominant position with stable, predictable earnings - they're almost bond-market like."

Earnings before items in the quarter rose $970 million from $910 million a year earlier, it said.

Singtel gets revenue from operations in its home market and Australia and dividends from stakes in emerging-market carriers including Indonesia's PT Telekomunikasi Selular, Bharti Airtel, and Thailand's Advanced Info Service Pcl.

The Singapore dollar weakened against all the three emerging countries' currencies in the quarter compared to a year earlier, increasing the value of earnings from the affiliates, according to data compiled by Bloomberg. It strengthened against the Australian dollar, reducing the value of Optus's profits.

Optus added 96,000 mobile customers in the quarter and average revenue per user increased 5 per cent. Optus earnings gained 6 percent with a 12 per cent surge in data revenue, Singtel said on Thursday