Egyptian security forces have detained a Shi'ite Muslim activist who campaigned for more rights for Egypt's tiny minority Shi'ite population, security sources and the man's lawyer said on Wednesday. Mohamed el-Derini, who runs a Shi'ite group called the Supreme Council for the Care of the Prophet's Family, was taken from his home on Monday, and is the second Shi'ite activist arrested in two months in Egypt, lawyer Hossam Bahgat said.