MOSUL, Iraq  Members of Al Qaeda in Mesopotamia have been holding up blood banks and hospitals at gunpoint, stealing blood for their wounded fighters rather than risk having them arrested at medical facilities, according to Iraqi doctors, employees at health centers and the Sunni insurgents themselves.

Iraqi health officials say the raids have been occurring for some time in provinces with large Sunni Arab populations and appear to signal an insurgency desperate to safeguard its core group of fighters. But the insurgents have a diminished ability to intimidate hospital staffs into caring for them directly and dwindling support among fellow Sunni Arabs, including doctors, the officials said.

The Iraqi security force members that guard medical facilities have often stood idly by as the armed robberies take place, according to workers. This has reinforced doubts about Iraq’s ability to take on even a diminished insurgency as the United States continues to reduce its troops in the country.

Hadad Hamad, a doctor in Anbar Province, said the raids occurred in western Iraq as early as 2005, when “Al Qaeda fighters burst into Al Qaim Hospital’s blood bank, seized large quantities of blood and took it” to a nearby village, apparently to treat their wounded.