Apple has said it will "fully investigate" reports that a woman was electrocuted in China while trying to use an iPhone while it was recharging. The 23-year-old's brother has given an interview saying that her family believes she received a shock when trying to answer a call on the handset. News agency Xinhua has confirmed police are investigating the death of Ma Ailun in the north-western city of Xinjiang. But it said they had not verified if a mobile phone was the cause. Ms Ma's older sister posted a message on the micro-blogging service Sina Weibo following her death on Thursday. "[I] hope that Apple Inc can give us an explanation. I also hope that all of you will refrain from using your mobile devices while charging," it read. Xinhua said the message had been reposted more than 3,000 times. "We are deeply saddened to learn of this tragic incident and offer our condolences to the Ma family," Apple said in a statement. "We will fully investigate and co-operate with authorities in this matter." Safety advice According to local reports Ms Ma had been a flight attendant with China Southern Airlines and had been planning to get married in August. Her sister said she had bought the iPhone 5 shortly after it launched in the country in December and had been using it with the original charger at the time of the incident. Xinhua said the China Consumers Associations had previously reported a man had been killed in 2010 while making a phone call using a handset connected to the mains with an unauthorised charger. However, one UK-based expert said that under normal circumstances mobile phone owners had no reason to be concerned. "Using a handset while it's recharging should be completely safe," Prof Will Stewart, from the Institution of Engineering and Technology, told the BBC. "The charger output is low voltage - it's about five volts - much too unpowerful to be dangerous, therefore there should be no risk at all. "Having said that, something in the charger could have had a fault on it and/or the mains wiring it was connected to might have been faulty. "Owners should also avoid using mains-connected equipment whilst in the bath or if they are extremely wet, because water could run down the wire and into the plug." Apple reported that it had sold $8.8bn (£5.8bn) of goods in China over the January-to-March quarter, with iPhones sold from its 11 stores in the country in addition to 19,000 other third-party retailers.