Aug 12 (Reuters) - Australian wealth manager AMP Ltd said on Thursday its first-half underlying profit rose 57%, helped by stronger AMP Bank earnings and investment income from Group Office division, though the company did not declare an interim dividend.

Underlying net profit after tax from the company's retained businesses rose to A$181 million ($133.40 million), from A$115 million reported a year earlier. ($1 = 1.3569 Australian dollars) (Reporting by Soumyajit Saha and Arundhati Dutta in Bengaluru; Editing by Shailesh Kuber)