More than 500 million parcels are expected to be delivered during the sales promotion week around Nov. 11, known as "Singles' Day," an official predicted on Tuesday.

Liu Jun, deputy director of the State Post Bureau, said the amount of deliveries during this year's "Singles' Day" shopping spree will rise nearly 50 percent year on year.

"The peak is expected to come one or two days after Nov. 11 and over 90 million parcels will be delivered on a single day, up about 40 percent from the same period last year," said Liu.

Now in its sixth year, Singles' Day has become an important sales promotion event in China and a huge boon for e-commerce.

Last year, Alibaba, China's e-commerce giant and the original promoter of Singles' Day, posted an 83-percent year-on-year increase on its two online platforms -- Tmall.com and Taobao.com -- with sales totaling 35 billion yuan (5.69 billion U.S. dollars) thanks to the shopping spree.

However, a spurt of deliveries heavily burdened logistics and courier companies, with many buyers complaining about delayed parcels.