* Q1 core profit 412 mln euros vs market consensus 417 mln
* Repeats outlook of revenue down 1-2 pct, core profit down 3-4 pct (Adds details on operational performance, shares)
BRUSSELS May 9 Belgian telecoms operator Belgacom reported a sharper than expected fall in first-quarter core profit as revenues from its international carrier business disappointed and mobile income continued to decline.
The international carrier business, which gives wholesale access to telecom operators for routing international calls, showed a 15 percent fall in revenues as it lost business in Asia and regulatory caps on charges for routing calls in the EU hit.
The group repeated its 2014 guidance for a 1 to 2 percent fall in revenues, excluding the carrier business, with core profit declining between 3 and 4 percent
At 0820 GMT, Belgacom's traded 1 percent lower, making them the weakest performer on the Bel20 Index of leading Belgian shares which was broadly unchanged.
For the group as a whole, core profit fell to 412 million euros ($571.15 million), slightly below the 417 million expected in a Reuters poll of nine analysts.
The group also saw a drop in revenues for its consumer business, where a strong showing by its digital TV and broadband internet products did not make up for a fall in mobile phone revenue.
The Belgian mobile phone market is fiercely competitive due to a new law limiting customer contracts to six months, and revenues being capped by EU rules on roaming and routing charges.
Belgacom added 58,000 post-paid customers but lost 68,000 prepaid customers, performing better than some competitors.
Mobistar, Belgium's second largest mobile phone provider majority owned by France's Orange, lost 79,000 customers, 41,600 in post paid and 37.400 in prepaid, in the first quarter. ($1 = 0.7214 Euros) (Reporting by Robert-Jan Bartunek; editing by Philip Blenkinsop)