TOKYO — The operator of the decommissioned Fukushima nuclear power plant in Japan announced that the trial removal of radioactive waste from a damaged reactor planned for this week had been postponed due to a technical problem.

Tokyo Electric Power Co. (Tepco) had planned to remove a tiny sample of the estimated 880 tons of radioactive debris believed to be in the reactors of the tsunami-hit nuclear power plant.

After preparatory steps for the test recovery were completed on Thursday morning, a Tepco spokesman said the operator had “decided to stop the work”.

The sample removal will not continue on Friday because the operator needs to “investigate the cause of the malfunction,” another spokesman, Tatsuya Matoba, told AFP on Friday.

“We cannot rule out that we will start again this Saturday, but personally I have never seen such an operation start on a Saturday or Sunday,” he said.

He added that it was also unclear whether work would resume next week.

“It depends on how thoroughly we investigate,” he said.

Three of the six reactors at the Fukushima Daiichi nuclear power plant were in operation when a tsunami hit the plant on March 11, 2011. The cooling systems were destroyed and a core meltdown occurred. It was the worst nuclear disaster since Chernobyl.

In three blocks of the Fukushima nuclear power plant, fuel and other materials melted and solidified into highly radioactive “fuel residues”.

The tiny sample was to be examined for clues about the condition of the reactor’s interior and its dangerous contents – a crucial step towards shutting down the power plant.

The radiation levels in the rubble are so high that Tepco had to develop special robots that can withstand this radiation and work inside.

Its removal was long considered the greatest challenge in the decades-long project to decommission the Fukushima Daiichi nuclear power plant.

As part of preparations for the clearance task, Tepco deployed two mini-drones and a “snake-shaped robot” in one of the three nuclear reactors in February.

The latest probe, equipped with a robotic arm, is expected to take about a week to reach the radioactive remains inside the reactor and is expected to resurface with the sample next month.

Japan began discharging wastewater from the damaged power plant into the Pacific Ocean almost a year ago.

The move has sparked a diplomatic dispute with China and Russia.

Both countries have banned imports of Japanese seafood, although Tokyo insists that the discharge is safe – a view also supported by the United Nations nuclear agency.