A man, who set off a homemade bomb at Beijing Capital International Airport in July told a court the explosion was an accident and expressed remorse for his actions.

Ji Zhongxing, who appeared before a judge on Tuesday lying on a trolley bed and wearing hospital pyjamas, insisted the device exploded unexpectedly as he passed it from one hand to another.

"I did not intend it ... It was negligence," the 34-year-old said, according to a Sina Weibo post from Beijing Chaoyang District People's Court.