Thomson ReutersJanuary 24, 2013 05:30
* 50 officials involved in rare probe at ministry - sources
* Probe follows president's vow to fight graft
* Reforms in telecoms sector long delayed (Recasts, new details throughout)
By Aung Hla Tun
YANGON, Jan 24 (Reuters) - Myanmar's former telecommunications minister and dozens of officials are under investigation for graft, a senior government official said on Thursday, in a landmark probe in the fast reforming country long ranked among the world's most corrupt.