A radioactive forest within Chernobyl’s exclusion zone has caught fire, triggering a spike in local radiation levels.

On Sunday around 90 firefighters were deployed to fight the blaze, which a Ukrainian official said had spread over almost 250 acres, 50 of which were within the restricted area around the disused nuclear power plant.

“Firefighters continue to fight the fire that originated in the Chernobyl zone. The situation is difficult,” Yegor Firsov, Ukraine’s ecological inspection service chief wrote on Facebook Sunday morning.

Ukraine's emergencies service said one of the fires, covering about 12 acres, had been localised. It said the other fire was about 50 acres.

The discrepancy in sizes could not immediately be resolved.

Radiation levels were “above normal in the centre of the fire”, Mr Firsov said, adding it was “bad news”. But the emergencies service said radiation levels in the capital of Kyiv, about 60 miles south, were within normal levels.

The fires were within the 1,000-square-mile Chernobyl Exclusion Zone established after the 1986 disaster at the plant that sent a cloud of radioactive fallout over much of Europe.

The zone is largely unpopulated, although about 200 people have remained despite orders to leave.

Fires are relatively common in the forests surrounding the former nuclear plant. Mr Firsov said the latest blaze was likely caused by people setting fire to nearby grass, which then spread to trees.

He called on the Ukrainian parliament to increase arson fines 100-fold, “otherwise, large-scale fires will continue to happen every fall and spring”.