Facebook's temporary block on a link to Kirk Cameron's new movie website was down to a mistake in their anti-spam systems, the social networking site has explained.

Cameron, best known for his lead role in Fireproof, posted a link to his new film, Unstoppable, on his Facebook page last week.  

However, he later posted to his 653,000 fans that Facebook had blocked the link.  

"Facebook has officially 'blocked' me and you (and everyone else) from posting any link to my new movie at UnstoppableTheMovieDOTcom, labeling the content as 'abusive', 'unsafe', and 'spammy'," he wrote.

"This is my most personal film about faith, hope and love, and about why God allows bad things to happen to good people.

"What is 'abusive' or 'unsafe' about that?!  Please help us encourage Facebook to unblock our website soon by sharing this post with your friends so more people can see this transparent, faith-building project." 

Last Friday, Cameron updated fans telling them that the block had been lifted.  

"Because of your firm, loving, and clear voice, not only did Facebook welcome us back, YouTube also removed its block on our Unstoppable movie trailer. We are back online with full access," posted Cameron.

"Now let's make sure NOTHING stops UNSTOPPABLE from coming to a theater in your town on Sept. 24th. Buy your tickets today. If we sell out all the seats in your neighborhood theater, NOTHING can stop it from playing there."

Explaining the block on the link, Facebook communications manager Michael Kirkland told The Christian Post that it had been mistakenly identified as a spamming site by its "automated" anti-spam systems.

"From what we can tell, the address purchased for the movie was previously being used as a spam site and it hadn't been refreshed in our system yet," said Kirkland.

"We were in direct contact with Kirk's team on this and reversed the block as soon as we confirmed that the address was no longer being used for spam."

He added: "These [anti-spam] systems are so effective that most people who use Facebook will never encounter spam. They're not perfect, though, and in rare instances they make mistakes.

"This link was blocked for a very short period of time after being misidentified as a potential spam or malware site. We learn from rare cases such as these to make our systems even better."

Watch the trailer for Unstoppable here: