San Francisco, Jan 25 (IANS): Despite facing criticism that its two-question users' survey to curb the spread of fake news could be manipulated, Facebook has defended the survey in a series of tweets.

According to Adam Mosseri, Head of News Feed, Facebook will sample a new set of users each day.

"There is always the risk that people will try and game any system. In this case we (1) randomly sample people, (2) actively work to de-bias the data so it's representative of the population and (3) re-run the surveys every day," Mosseri tweeted on Thursday.

"It's worth noting this isn't a rating system, nobody can opt into rating a publisher as trustworthy.

"We randomly sample new people each day, and only their responses are used. I'm sure some bad actors will try and game the system, but it's not as easy as you suggest," he tweeted to one user who criticised the survey.

The two survey questions are: "Do you recognise the following website? Yes or No" and "How much do you trust each of these domains? Entirely, A lot, Somewhat, Barely, Not at all".

Facebook CEO Mark Zuckerberg, in a lengthy post last week, revealed about the survey to determine sources that are "broadly trusted".

"As part of our ongoing quality surveys, we will now ask people whether they're familiar with a news source and, if so, whether they trust that source," he posted.

"The idea is that some news organisations are only trusted by their readers or watchers, and others are broadly trusted across society even by those who don't follow them directly," he added.

"This update will not change the amount of news you see on Facebook. It will only shift the balance of news you see towards sources that are determined to be trusted by the community," Zuckerberg noted.