More than 275 firefighters were on Saturday battling a challenging wildfire in Spain's southern Andalusia region, though authorities said no residential zone was currently at threat.

The blaze, happening north of the town of Niebla, halfway between Seville and the Portuguese border, was active in an area of around 4,000 hectares (9,900 acres), an adviser to Andalusia's emergency service, Antonio Sanz, said.

"This wildfire is driven by constantly changing winds, which up-ends attack strategies," he told reporters.

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He adding that a "window of opportunity" had opened Saturday for a few hours, before conditions again worsened later in the day.