Magen David Adom's blood supply has dipped below the red line, especially all Rh- blood types and O+ blood, MDA announced on Sunday. The shortage was caused by a decline in donors and an increase in hospital use of blood. As a result, some hospitals will likely be forced to postpone elective operations, and their ongoing activities will be disrupted. MDA announced a three-day blood drive at its stations in Jerusalem, Tel Aviv and Haifa and its Central Blood Bank at Tel Hashomer. It will be held through Tuesday between 8 a.m. and 9 p.m. In addition, MDA branches in Beersheba, Petah Tikva and Hadera will accept donors from 4 p.m. to 9 p.m. through Tuesday. More information can be obtained by calling (03) 530-0400. Organized groups of over 20 people should call (03) 5300402. Every donor receives blood insurance for a year for himself and his immediate family.