A senior Saudi cleric is urging Saudis not to donate to charities that might be channeling money to terror organizations. Grand Mufti Sheikh 'Abd Al-'Aziz 'Abdallah Al Sheikh warned about giving money to organizations financing what he called "harmful groups." The warning came just days after it was reported that Al-Qa'ida's second in command, Ayman A-Zawahiri, was spreading audio messages through cell phones in Saudi Arabia and appealing to Saudis to give money to charities for needy people in Pakistan and Afghanistan. The cleric said funds should not be given to everyone who asks, and especially if they have harmed Islam and its followers, according to the Saudi daily Al-'Ukaz. Meanwhile, the Saudi Interior Ministry is warning that anyone who responded to A-Zawahiri's appeals would be penalized, unless they approached the ministry within a week to "clarify their position." Saudi Arabia is an ally of the United States in the war on terror. The kingdom has been fighting Al-Qa'ida-inspired terrorism since May 2003, when several attacks were launched on compounds in Riyadh, killing 27 people, including American citizens. Terrorists linked to Al-Qa'ida have been targeting official institutions, diplomatic and economic interests and foreigners in an attempt to undermine the monarchy and drive out Westerners. Saudi security forces have arrested dozens of terror suspects of different nationalities since December. The detainees are under suspicion of planning terror attacks in the kingdom.