COTABATO, the Philippines, Nov. 7 (Xinhua) -- Suspected Al-Qaida affiliated militants tossed a grenade early Saturday at abandoned Roman Catholic Church in the volatile southern Philippines but there were no reported casualties.

    Philippine military regional spokesman Major David Hontiveros told reporters the steel fence of San Isidro Labrador church was partially damaged in the blast that occurred shortly before 1:00 a.m. in the village of Talon-Talon in southern city of Zamboanga.

    No one was hurt in the attack and state bomb experts have recovered fragments of grenade at the site.

    Hontiveros said authorities have recovered a letter left by attackers addressed to the mayor of Zamboanga, Celso Lobregat, but the content was not divulged to reporters.

    No one claimed responsibility for the grenade attack but the Philippine military and police blamed Muslim militants under Abu Sayyaf in previous bombings in the region.

    Abu Sayyaf, a group blacklisted by Washington as a foreign terrorist organization, is considered a major security threat to the Philippines for their involvement in kidnappings, bombings and even beheadings in the South over the past decade.