A decontamination system at Japan’s troubled Fukushima Daiichi nuclear plant has again been halted due to malfunction.

Tokyo Electric officials say they shut down the Advanced Liquid Processing System yesterday (Monday).

The ALPS filters radioactive substances from water used to cool melted fuel inside the reactors.

Officials say they stopped the system after finding water containing high levels of strontium even after it passed through a filter.

Two of three lines were already shut down due to operational errors.

Now, all three are offline.

Officials say the water is being cleaned with a different filter before it is stored in tanks.

Tepco is struggling with huge volumes of contaminated water building up at Fukushima Daiichi since the 2011 disaster.