An anti-spam computer algorithm is being blamed by Facebook (News - Alert) for blocking environmental activists and several other users.

The users were told they could not post for 15 days on the social media site, according to a report from The Associated Press.

Many appeared confused over what happened when they could not post to pages. Then, last week, several users got the following message from Facebook, “Your account was mistakenly blocked from posting on Pages. We apologize for any inconvenience this has caused. We've lifted the block from your account, and you should now be able to post again.” However, not everyone found they could again post, The AP said.

Facebook said it is improving its automated system, according to The AP.

“Facebook is not — and has never been — in the business of disabling accounts or removing content simply because people are discussing controversial topics,” Facebook’s Andrew Noyes told The AP. “On the contrary, we want Facebook to be a place where people can openly express their views and opinions, even if others don't agree with them.”

The activists were simply identified by an anti-spam program that kept them from posting, The AP said.

“Our systems classify over 10 billion actions (suspicious logins, friend requests, etc.) and pieces of content (messages, Wall posts, etc.) every day,” Noyes told The AP. “Of course, no system is perfect, and we do sometimes make mistakes.”

“The first feeling was surprise, because I'd been doing this for over a year, with no problem,” Gloria Forouzan of Pittsburgh, who has been protesting natural gas drilling, told The AP. “Then I found out a few others were blocked, and we all started getting angry.”

An animal rescue activist had similar problems.

Facebook, like other social media sites, use automated programs to protect against spam, the AP said. In addition, there is an appeals system at Facebook if personal accounts are disabled, but not for the 15-day spam sentence, The AP said.

Facebook has said that its automated systems are programmed to identify and block spam when “appropriate,” according to a story carried by TMCnet.

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