The operator of the troubled Fukushima Daiichi nuclear power plant says five workers there may have been exposed to several liters of liquid containing radioactive substances, instead of about 100 milliliters as initially announced.

The workers were accidentally splashed with the liquid last Wednesday when they were cleaning pipes for the plant's Advanced Liquid Processing System, or ALPS. The system is used to treat water that accumulates at the plant.

Two of the workers, one in his 20s and the other in his 40s, were hospitalized for decontamination treatment. They were released from the hospital on Saturday after their body radiation levels had fallen below a certain level.

Tokyo Electric Power Company had initially said that about 100 millimeters of the liquid had gushed out from a hose, estimating from the amount of the liquid left on the floor.

But on Monday, the utility told reporters it has been found that the amount of splashed liquid is likely as much as several liters, based on witness accounts of workers at the site and the floor area with traces of the liquid.

The company also says it is considering revising rules at the worksite as the two hospitalized workers, who were in charge of observing the cleaning work, were not required to wear waterproof suits.