Grade's intervention will add weight to the argument that Ofcom should make a referral to the Competition Commission after carrying out its initial investigation.
The investigation comes after Trade Secretary Alistair Darling last month instructed Ofcom to investigate Sky's 17.9% stake in ITV on "public interest grounds".
Grade said he had written letters to all three organisations, but had not discussed his concerns with James Murdoch, the BSkyB chief executive.
He said: "The only issue is that Sky could theoretically and practically block any major move that we wanted to make."
That "may not be in the interests of ITV's shareholders as a whole," Grade said, adding that he and the board were "anxious to represent the views of all shareholders".
Separately, Grade has expressed an interest in expanding ITV's production arm, possibly through the acquisition of foreign groups.
He said: "We may be interested in bolt-on acquisitions to increase our overseas presence." However, Grade refused to comment on whether ITV would bid for Endemol, the producer of Big Brother.
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