Under the updated guidelines AP journalists are told their "first obligation" in the case of a big breaking news event, "is to provide full details to the appropriate newsdesk for use in AP services if the desk isn’t tuned in already".
But once they have informed the newsdesk and taken care of "any other immediate AP work" they are now "free to tweet or post information about the news development" on Twitter.
Previously the guidance, which was last updated in January, said that content needed to move on to the wires first.
AP's social media editor Eric Carvin told Journalism.co.uk this has now been replaced with a "more detailed breakdown of what to do in different circumstances".
This includes a clarification that the live-tweeting of a public, live broadcast news event that could be followed by anyone "is fine", Carvin said.
In the case of big breaking news stories, providing they are not exclusive, once the newsdesk has been informed and if the journalist is not required to write the story, then they are free to tweet about it.
As for exclusive content, the guidelines state that "AP news services must have the opportunity to publish exclusive text, photo and video material before it appears on social networks".
"Once that material has been published, staffers are welcome to tweet and post a link to it on AP or subscriber platforms".
He added that it was important that these guidelines be written down and clarified, but did not constitute a "dramatic change".
The guidance also addresses retweets, which "like tweets, should not be written in a way that looks like you’re expressing a personal opinion on the issues of the day".
"A retweet with no comment of your own can easily be seen as a sign of approval of what you’re relaying", the guidance adds.
The guidelines also feature a note about "the safety of AP staff", with journalists told not to publish on social media "any information that could jeopardise the safety of AP staff", such as the whereabouts of journalists working in potentially dangerous locations or reports on the arrest of staffers.
Last year executive editor of the Associated Press Kathleen Carroll claimed the company's policies were "violated" when journalists tweeted about the arrest of colleagues covering the Occupy Wall Street protests.
The updated guidelines also offer advice on how journalists should interact with politicians on social networks.
The guidelines state: "It is acceptable to extend and accept Facebook friend requests from sources, politicians and newsmakers if necessary for reporting purposes, and to follow them on Twitter.
"However, friending and 'liking' political candidates or causes may create a perception among people unfamiliar with the protocol of social networks that AP staffers are advocates.
"Therefore, staffers should try to make this kind of contact with figures on both sides of controversial issues."
Previously journalists were advised to use lists instead of "liking" the Facebook page of a politician, for example, apart from some exceptions where using "like" was essential.