Chinese courier companies are braced for a surge in shipments over the coming days, as Singles' Day, the world's largest online shopping day, is approaching.

Liu Jun, deputy director of the State Postal Bureau, said couriers are expected to deliver more than 1 billion packages in the days following Singles' Day on Friday, 35 percent up on last year, Liu said.

Singles' Day started as Bachelors' Day in China in 1990s. While the day was then celebrated by drinking and partying, it has been hi-jacked by online retailers in recent years and become another massive extravaganza in consumption.

Singles' Day sales already dwarfs Black Friday in the U.S. and Boxing Day in the U.K. Sales on just one shopping site, Tmall were 91.2 billion yuan (around 14 billion U.S. dollars) in 2015. Some analysts expect sales to rise by as much as 50 percent this year.