iPhone 5s battery expanding

HI,

Recently the battery on my iPhone 5s started expanding, causing the screen to pop out. I stopped using the phone but the battery has expanded more, it has reached a stage where I fear it may explode because the battery is so swollen. The screen now sticks out about 1.5 inches in some places. My phone is out of warranty, will apple replace the phone. Surely it is a fire risk? What should I do?

Thanks