A courier carries packages at a sorting facility of STO Express Ltd in Fuyang, Anhui province, during the Nov 11 shopping festival last year. More pictures

Singles Day sales are set to get crazier this year, with transactions and deliveries expected to break records amid public concerns about quality.

The shopping festival is similar to Black Friday and Cyber Monday in the United States, but it is the world's largest online sales event.

E-commerce giant Alibaba Group Holding, which created the annual November 11 event, is expected to reach a new high on Friday, with a 40 percent surge as bargain-hunting Chinese consumers flex their spending muscle, according to a report released on Nov 2.

Singles Day sales at Alibaba this year are expected to jump to $20 billion from last year's $14.3 billion. The 2015 figure represented a year-on-year increase of 54 percent, the report said.

The shopping spree is a peak season for the logistics industry.

China Post, China's postal service, estimated that 760 million packages will be generated by Singles Day sales, compared with 540 million last year. Couriers have advertised to hire extra people to handle the seasonal workload increase.

"Singles Day 2016 is expected to be bigger than ever. It's no longer just a one-day online shopping festival, with retailers introducing promotions that start before and end after November 11," said Wang Xiaofeng, a senior analyst at Forrester Research.

"It is also going global, extending beyond China and Asia to include many international retailers who offer attractive discounts and more efficient cross-border shipping," she said.

Cut-to-the-bone prices used to be the main driver of the event. But a recent report from Nielsen said that apart from sales and discounts, the quality of goods is also a main factor in determining which e-commerce company consumers choose.

Ministry of Commerce spokesman Shen Danyang said the ministry will cooperate with other government organizations to monitor the behavior of e-commerce platforms during the event.