UPDATE 2-SingTel Q3 underlying profit rises on Airtel's upbeat earnings

(Adds details on net profit)

Feb 16 (Reuters) - Singapore Telecommunications on Thursday posted a more than 18% jump in third-quarter underlying profit, driven by the strong performance of associate Bharti Airtel.

All segments of SingTel's business benefited from a sustained recovery in international travel, driving up the roaming revenue and the number of prepaid customers.

Bharti Airtel, India's No.2 telecom carrier by subscribers, reported a bigger-than-expected increase in third-quarter revenue earlier this month, helped by 4G subscriber additions and higher revenue per user.

SingTel, which is Southeast Asia's largest telecom firm, reported underlying net profit of S$559 million ($418.54 million) for the quarter ended Dec. 31, compared with S$473 million a year earlier.

Mobile revenues from Australian unit Optus, which reported a data breach of up to 10 million customers in October, came in at A$1.40 billion ($967.82 million), compared with A$1.32 billion a year earlier.

However, SingTel's net profit for the quarter fell to S$532 million, compared with S$734 million a year ago when it recorded a one-off gain from disposal of 70% stake in a unit. ($1 = 1.3356 Singapore dollars) ($1 = 1.4480 Australian dollars) (Reporting by Jaskiran Singh and Harish Sridharan in Bengaluru; Editing by Shailesh Kuber and Dhanya Ann Thoppil)