Samsung is stopping worldwide sales and exchanges of its Galaxy Note 7 smartphone, citing continued safety concerns, and advising all customers to stop using the device immediately. The company Tuesday asked all Galaxy Note 7 owners to turn off the power on the device and seek a refund or exchange them for different phones. "We are working with relevant regulatory bodies to investigate the recently reported cases involving the Galaxy Note 7," Samsung said in a statement. Share prices of the South Korean conglomerate plunged by as much as seven percent by mid-Tuesday's stock market trading session. The announcement follows several new incidents of overheating last week and deals a further blow to the world's largest smartphone company. U.S. consumer safety officials said they are investigating five incidents of fire or overheating since the company announced a recall last month. Officials from the U.S. Consumer Product Safety Commission echoed advice in their own statement. "No one should have to be concerned their phone will endanger them, their family or their property,'' said Elliot Kaye, chairman of the safety commission. He called Samsung's decision to suspend all sales "the right move'' in light of "ongoing safety concerns.'' Samsung's decision to pull Note 7s off the shelves for the second time in two months underscores the firm's struggles to fix its problems. It had already recalled 2.5 million Note 7s due to faulty batteries, but the latest reports of damage on the replacement devices is raising fresh doubts about the firm's quality control abilities. But analysts say the move comes a little late given that a number of major distributors, including U.S. telecom firm AT&T and German rival T-Mobile, unilaterally announced a halt to sales and exchanges of the model on Sunday. The top-of-the-line Note 7 was crucial to Samsung's growth plans this year, with the company struggling to boost sales, squeezed by Apple in the high-end sector and Chinese rivals in the low-end.