Tokyo Electric Power Co., the plant's operator, last week confirmed about 79,000 gallons of radioactive water leaked from a storage tank. It warned there may be hundreds more tanks like it on the site of the 2011 meltdown.
The Japanese government said it is frustrated with Tepco's inability to resolve the situation on its own.
"This water issue won't be solved if we leave it to Tepco," Japanese Minister of Economy, Trade and Industry Toshimitsu Motegi was quoted by The Wall Street Journal as saying Tuesday. "We will take an active role both in reinforcing staff and covering costs."
Fukushima melted down in 2011 following a 9-magnitude earthquake.
Motegi said the government would build "underground ice shields" to prevent groundwater from seeping into the contamination zone.
The government said the incident is a "serious" nuclear event, or level 3 on an international scale. The meltdown itself was categorized as a level 7 nuclear event, the highest level.