LONDON, July 28 (Reuters) - European information and analytics provider Relx increased its interim dividend by 10% on Thursday and reiterated its full-year outlook, saying it expected underlying growth rates to remain above historical trends.

Relx, traditionally one of the most reliable performers on the London stock exchange, posted a 16% rise in first-half adjusted operating profit.

"As we enter the second half, momentum remains strong across the group, and we continue to expect full year underlying growth rates in revenue and adjusted operating profit, as well as constant currency growth in adjusted earnings per share, to remain above historical trends," it said. (Reporting by Kate Holton Editing by William Schomberg)