SingTel, Southeast Asia's biggest telecom firm, reported on Monday a net profit of S$902 million for the quarter ended December, down from S$998 million a year ago.

The profit lagged the average forecast of S$922 million by four analysts surveyed by Reuters. The underlying net profit was S$895 million, 7.6 percent below the S$968 million posted a year ago.

"The strong gain in mobile customers in Singapore during the quarter led to higher acquisition and retention costs, while contributions from the regional mobile associates declined due to their weaker currencies and 3G losses from Bharti India," SingTel said in a statement.

SingTel's earnings in recent quarters has been dragged by the $9 billion acquisition of African mobile phone operations by Bharti in 2010.