Shanghai is encouraging eligible residents to give blood because the blood supply is has fallen to insufficient levels.

The city currently has about 6700 units of blood available per day, while the normal daily level is 9000 units, the Shanghai Blood Administration Office said.

The current blood supply is sufficient only for emergencies and first aid. Some hospital surgeries have had to be postponed because of the unavailability of blood,an official from the administration said.

Authorities are encouraging residents between ages 18 and 55 to give blood.