Amid the controversy surrounding deliberate iPhone slowdowns, Apple might have another problem to deal with – the explosion of the batteries in the phones. On Wednesday (10 January), an iPhone battery exploded in Spain, just a day after a very similar incident was reported in Switzerland.

The explosion occurred at Apple's Calle Colón Store in Valencia, Spain. According to a report in Las Provincias, the battery overheated while being worked upon and started emitting smoke, triggering immediate evacuation from the building. An entire floor in the building was engulfed in smoke, one of the first responders at the site reported.

Emergency services were called but store workers had managed to control the situation by covering the battery with sand. No injuries were reported at the scene. It remains unclear which iPhone model battery exploded or why it exploded.

On Tuesday, an iPhone 6S battery exploded at an Apple Store in Zurich, Switzerland, burning the hand of a repairman who was removing it from the device.

About 50 people were asked to evacuate the store at Bahnhofstrasse 77 as police and firefighters attended the site. Along with the burnt worker, six other people received medical treatment for unspecified injuries but none of them was taken to hospital.

"The staff responded well and correctly," Zurich City police said in a statement, according to local media outlet Swissinfo. "They sprinkled quartz sand over the overheated battery so that the smoke could be contained and sucked out after switching on the ventilation."

Forensic experts are looking into the incident in Zurich but the exact cause of the explosion is not yet known.

The reports come as Apple continues to face flak for slowing down older iPhones in a bid to bolster their battery life. The company has been hit with several lawsuits in the wake of its admission and it has promised a discounted battery replacement programme for all affected iPhones.

An official statement from the Cupertino-based giant regarding the battery explosions is still awaited. IBTimes UK has reached out to Apple and will update this story once a response is received.