Héma-Québec is gradually lifting the restrictions on thousands of blood bags that were pulled out of circulation because of possible manufacturing defects just over a week ago.

Concerns about micro-leaks in the connecting tubes used to fill the bags had officials worried about the blood being exposed to air. The exposure could have created the conditions for bacterial growth.

The blood collection agency said it is testing all of the containers and said no signs of contamination have been found yet.

According to Héma-Québec, nearly 4,000 bags of blood were set aside. The temporary shortage forced some hospitals to cancel or delay non-urgent operations.

Despite the precautions, the agency said it had enough blood on reserve to keep up with the hospitals' demands.