BEIRUT, July 30 (Reuters) - Lebanon's Byblos festival has cancelled a concert by Lebanese band Mashrou' Leila which was set for next week after calls from church leaders who accused the group of blasphemy.

The band, which has an openly gay vocalist and has played in major cities around the world, has said it is the target of a smear campaign in Lebanon to crush freedom of expression. The musicians have received threats on social media in recent weeks.

"In an unprecedented move...the committee was forced to stop the Mashrou Leila show...to prevent bloodshed and preserve security," the major summer music festival, in the ancient city of Byblos, said in a statement. (Reporting by Ellen Francis, Editing by William Maclean)