INTERNATIONAL Bank of Asia (IBA) yesterday reported a half-year net profit of $58.3 million, up 38 per cent from last year. ''The retail strategy put in place at the end of 1988 has established a foundation for strong all-round performance, including net interest income, fees and income from subsidiaries,'' said Mike Murad, IBA vice-chairman and chief executive. Total assets at June 30 were $9.6 billion and return on assets was at 1.9 per cent. Owned by the Bahrain-based Arab Banking Corp, IBA reported an increase in loans and advances of 22 per cent to $6.3 billion, with less than 30 per cent in the form of residential mortgages. ''Such diversification will continue to be emphasised,'' Mr Murad said. He attributed the growth to the introduction of new bank products, branch expansion, flourishing trade finance and successful credit card promotional programmes. The bank will open its 20th branch in Chai Wan next month. The purchase of its head-office building at 38 Des Voeux Road was completed last month.