Russia's Megafon posts 57 pct rise in Q1 telecom earnings

* Cuts forex losses by 747 mln roubles

* Gets boost from new accounting standards

* Core profit up 5 pct on revenue up 3 pct (Adds detail)

MOSCOW, June 21 (Reuters) - Megafon, Russia's No.2 mobile phone operator, reported a 57 percent jump in its telecom segment first-quarter net profit to 6 billion roubles ($94 million) helped by smaller foreign exchange losses and a switch to new reporting standards.

Stripped of a 450 million rouble boost from a transition to new accounting standards, Megafon's net rose to 5.6 billion roubles, up 45.5 percent.

The mobile phone operator said it had cut forex losses by 747 million roubles.

Operating income before depreciation and amortisation (OIBDA) rose 5.3 percent to 30.6 billion roubles and the company repeated it was expected to stay flat in full year 2018.

Revenue rose 2.6 percent to 76.5 billion roubles, driven by an 11 percent rise in mobile data services sales.

Megafon reported a negative free cash flow of 153 million roubles which it attributed to a settlement of large trade and other payables such as payments to suppliers and employee bonuses.

Its total net debt fell to 231.8 billion roubles from 234.5 billion roubles at the end of 2017.

The results do not take into account internet group Mail.ru in which Megafon bought a stake in 2017.

($1 = 63.7925 roubles) (Reporting by Maria Kiselyova; editing by Jason Neely)