WASHINGTON (BLOOMBERG) - Alphabet's Google posted internal rules that discourage employees from debating politics, a shift away from the internet giant's famously open culture.

The "community guidelines" tell employees not to have "disruptive" conversations and warn workers that they'll be held responsible for what they say at the office.

Google is also building a tool to let employees flag problematic internal posts and creating a team of moderators to monitor conversations on company chat boards, a spokeswoman said.

"While sharing information and ideas with colleagues helps build community, disrupting the workday to have a raging debate over politics or the latest news story does not," the policy states.

"Our primary responsibility is to do the work we've each been hired to do."

Google has long encouraged employees to question each other and push back against managers when they think they're making the wrong decision.

Google's founders point to the open culture as instrumental to the success they have had revolutionising the tech landscape over the last two decades.

But the free-wheeling culture has led to a rash of problems for Google management in recent years.

Some employees have used internal chat boards to rally other workers against some Google projects, helping push the company to end work on a censored search engine for the Chinese market and an artificial intelligence contract for the US military.

"I think it's specifically intended to silence dissent," Irene Knapp, an engineer at Google, said.

"This is the end of the important parts of Google's open culture.

"Ultimately, business interests will always win out over ethics in terms of what we're allowed to say," Knapp said.