Liyakatali Takim, Professor Liyakat Takim is the Sharjah Chair in Global Islam at McMaster University in Canada. Answer imported 4 years ago

The Maraji' have generally ruled that wearing things like leather belts in salat is not allowed if the leather is not slaughtered in an Islamic way. See Islamic Laws of Ayatullah Seestani's Tawdhihu'l Masa'il p. 160.