May 23 (Reuters) - Singapore Telecommunications posted a 64% drop in full-year net profit on Thursday hit by a S$3.1 billion ($2.30 billion) impairment charge, majority of which relates to its mobile network operation unit Optus.

Australia's second-largest telecom company Optus has been marred by multiple setbacks, including a massive network-wide outage in the country, data breaches and steep declines in fixed carriage revenue amid increased capital costs.

The non-cash charge comprises a S$2 billion provision on the goodwill of Optus, while S$470 million relates to Optus' enterprise fixed access network assets.

Excluding the one-time charge, company's underlying net profit rose 10% to S$2.26 billion, underpinned by higher contributions from regional associates including Airtel and Advanced Info Service.

Southeast Asia's largest telecom firm said net profit for fiscal year 2023 was S$795 million, compared with S$2.23 billion a year ago.

The telco forecast a earnings growth rate of high single digits to low double digits for fiscal 2025, adding that it was focused on lifting core performance at Singtel Singapore and Optus and scaling growth engines such as NCS and Nxera with a leaner cost structure.

Revenues from Optus, the company's top revenue generator, was largely unchanged at A$8.06 billion ($5.34 billion).

"Optus is working hard to rebuild the trust of customers after a challenging 18 months and these results demonstrate we are on the right track," Optus interim CEO Michael Venter said.

SingTel proposed a final dividend of 9.8 Singapore cents per share, compared with 5.3 Singapore cents a year earlier.

The company also unveiled a revised dividend policy, which includes a new value realisation dividend of 3 to 6 Singapore cents per share per annum, on top of the core dividend, helped by its capital recycling programme.

SingTel has further identified a pipeline of around S$6 billion of assets that can be potentially recycled over the medium term to return excess capital to shareholders through the value realisation dividend.

($1 = 1.5103 Australian dollars) (Reporting by Ayushman Ojha and Shivangi Lahiri in Bengaluru; Editing by Shailesh Kuber and Rashmi Aich)