Among those making the report was former England batsman Chris Broad, now a match referee, who earlier this year raised similar concerns about Sri Lanka's former Test wicket world record-holder Muttiah Muralitharan's 'doosra', a delivery which turns away from a right-handed batsman - the opposite of an orthodox off-spin ball.
In a statement, the ICC said the report had been made following the conclusion of Monday's second Test between Bangladesh and India in Chittagong where Harbahajan took two for 19 in the hosts's second innings during an innings and 83 run-win that saw India clinch the series 2-0.
As well as Broad, the ICC said the report was made by on-field umpires, Aleem Dar (Pakistan) and Mark Benson (England) and the TV umpire, Mahbubur Rahman (Bangladesh).
ICC chief executive Malcolm Speed said: "Having closely reviewed the action Harbhajan Singh employs during this delivery, the match officials decided to report the bowler to the ICC and, in line with the protocol, notified the India team management of this course of action."
He added: "Harbhajan Singh will now work with an expert team over the next six weeks to address these concerns. He can continue to play international cricket and cannot be reported again during this period."
Although the ICC ultimately has the power to ban from international cricket any bowler it considers has an illegal action, its rules for dealing with such cases are currently in limbo.
A committee made up of former Test players, chaired by former India captain Sunil Gavaskar, has recommended a new rule allowing bowlers to straighten their arms by up to 15 degrees.
The new rule varies the amount of straightening allowed depending on the type of bowling. Under exisiting regulations spinners are restricted to five degrees, medium pacers to seven and a half degrees and fast bowlers to 10 degrees.
Under the proposed ruling, which will be put to the ICC chief cxecutives' committee of the 10 Test-playing countries at its next meeting, in Melbourne, Australia, in February, almost all modern bowling actions would be classfied as legal.
Tests showed that Muralitharan's elbow straightened by 14 degrees, nine degrees more than the current limit for spinners, when bowling the doosra.
Extensive research into the biomechanics of bowling over the past four years has revealed that almost every bowler straightens his arm before letting go of the ball.
This is not the first time Harbhajan, nicknamed the 'Turbanator' on account of the head covering he wears as a Sikh, has had his action come under official scrutiny.
Back in 1998 he was forced to undergo remedial work in London where former England off-spinner Fred Titmus helped him remodel his action.