Two emergency blood transfusions failed to raise Emperor Hirohito's blood pressure Thursday, leading to fears that prolonged internal bleeding may have sapped the ailing monarch's strength, officials said.

The 87-year-old monarch was administered 1.72 pints of blood in two transfusions during the day, but his systolic blood pressure remained at 74 by evening, Imperial Household Agency spokesman Kenji Maeda said.An average systolic, or upper, blood pressure reading is about 120. Pressure of less than 100 for sustained periods can lead to permanent damage of the brain and internal organs.

The emperor's blood pressure dropped suddenly early Thursday, and he was immediately given the first transfusion. Maeda said the second came in the late afternoon.

The low blood pressure indicates Hirohito continues to lose blood internally, and although no discharges were reported Thursday, "the lost blood may still be in his body," said a palace official who requested anonymity.

Doctors fear the emperor is weakening and are focusing their efforts on lifting his blood pressure, the official said. Previously, doctors concentrated on averting large blood losses, but now "the emperor might not have enough energy to discharge a large amount of blood," he added.

Transfusions have been a major treatment since the emperor fell ill in mid-September, and as of Thursday evening he has received 67.83 pints of blood.