The sources declined to be identified due to the sensitivity of the issue, while a statement from Ranbaxy did not give details about the impact of the suspension.
Last month, the US Food and Drug Administration (FDA) prohibited Ranbaxy from shipping to its biggest market any pharmaceutical ingredients made at its facility in Toansa in Punjab.
The sanction was the latest in a series of regulatory rebukes for India's largest drugmaker by revenue since Japan's Daiichi Sankyo Co Ltd <4568.T> took control of the company in 2008.
The Toansa ban, which followed similar action on two plants in 2008 including Dewas and another in September 2013, means Ranbaxy can no longer export to the US from India.
Ranbaxy said in a statement on Tuesday it was "currently examining processes and controls" at all its active pharmaceutical ingredients (API) manufacturing units.
"This voluntary decision was taken as a precautionary measure and out of abundant caution to better allow the company to assess and review the processes and controls," it said in the statement.Ranbaxy also said it has set up a committee to provide oversight on manufacturing and quality operations, systems, organisation and integrity.