DUBAI, July 28 (Reuters) - Qatar Navigation (Milaha) posted a 25.7 percent rise in first-half net profit, it said on Tuesday.

The shipper's net profit was 651 million riyals ($178.8 million) for the first six months of 2015, compared with 518 million riyals in the same period of the previous year.

Reuters calculations show the firm made a net profit of 286.0 million riyals in the second quarter, compared with 168.9 million riyals a year earlier. It did not provide a quarterly breakdown of its earnings.

The shipping firm in April warned of a challenging 2015 due to weakening offshore business demand.

(Reporting by Hadeel Al Sayegh; Editing by Andrew Torchia) ((Hadeel.AlSayegh@thomsonreuters.com; +971566883310;))

Keywords: MILAHA RESULTS/