'Tis the season to be merry - and wary.

As consumers hit the Internet for their year-end holiday shopping, the police are stepping up efforts to help them guard against e-commerce scams, which typically spike during this period.

This year's crime prevention campaign by the police and the National Crime Prevention Council (NCPC) aims to help people become more informed about the most common scams, especially the ones involving online purchases.

The first half of this year has already seen 911 e-commerce scams, which took place mainly on the Carousell online platform.

Last year, there were 571 such cases from October to December, compared with the 499 to 549 in each of the previous three quarters. In 2015, the number of e-commerce scams hit 663 in the last quarter, while there were 448 to 566 in each of the other quarters.

Speaking at the campaign's launch at Chinatown Point yesterday, NCPC chairman Tan Kian Hoon noted that when people are busy during the festive period, they also tend to let their guard down.

"Today, eight out of 10 Singaporeans access the Internet, spending an average of two hours on social media daily. We also spend more time buying things online," he said.

"But technology is a double-edged sword, bringing about both convenience and threats."

Mr Tan noted that in the first six months of this year, Singaporeans lost $690,000 to e-commerce scams, more than $22 million to Internet love scams, and $21.9 million to e-mail impersonation scams. This means an average of $245,000 is lost to such scams every day, he said.

The campaign, which Mr Amrin Amin, Parliamentary Secretary for Home Affairs and Health, launched yesterday, will reach out to shoppers through street interviews and social media.

From Dec 9, the public may encounter actors taking on the role of "scammers" at different parts of Singapore, and through them learn how to identify the common scams. The people also get to vote for the "Most Unpopular Scammer" online. The campaign will run until March 19.

Explaining this year's initiative, NCPC vice-chairman Gerald Singham said: "We are trying to find new ways to reach out to the public. So when they vote, they may start to ask themselves, why is this 'scammer' unpopular? And they begin to think about or understand the different modus operandi."

During the year-end period, more officers, including those in plain clothes, will be deployed in shopping malls, police said yesterday.

They will, among other things, conduct checks if they find a person suspicious, and engage shoppers and retailers in crime prevention initiatives.

In particular, they will remind shoppers to look after their belongings and also alert the police to any suspicious persons or items.