Northern Spain is facing its largest forest fires in two decades as the heat wave scorching much of Europe continues to intensify.

The fires have swept across Spanish province of Tarragona, near Barcelona, with officials warning that it could eventually engulf as much as 20,000 hectares (200 square kilometers) of land.

"We're facing a serious fire on a scale not seen for 20 years. It could burn through 20,000 hectares. Let's be very aware that any carelessness could lead to a catastrophe," Miquel Buch, the interior minister for the Catalonia region said in a tweet.

Buch said that the cause of the largest of the wildfires was most likely the spontaneous ignition of a giant pile of manure which had been "improperly managed," according to CNN.

The Associated Press reported Buch as saying that the fire had started at a farm in the village of Torre de l'Espanyol, when a deposit of chicken manure overheated and set fire.

Spontaneous ignition is not uncommon in manure during times hot weather, because the process of decomposition in manure heaps creates heat. When it is particularly hot, like this week, temperatures in manure piles can rise high enough to start a fire.

"We're at a moment when the blaze is getting bigger," Buch, the interior minister, told local media, according to Deutsche Welle.

Local firefighters said that the wildfire was not yet under control.

"It's complicated. We won't get it stabilised today," regional fire chief Manuel Pardo told Spanish TV on Thursday, Deutsche Welle reported.

On Wednesday, Buch tweeted that more than 400 individual wildfires had started in the previous two days, thanks in part to the heat wave hitting Europe this week.

In some parts of the continent, temperatures are due to reach up to 45 C (113 F).

Scientists have attributed the soaring temperatures to the combination of a storm over the Atlantic Ocean and high pressure over central Europe, which is sucking in hot air from the Sahara.

This article was originally published by Business Insider.

More from Business Insider: