The Government is financially backing a last minute TVNZ-TV3 bid to screen the free to air games in competition against a MTS bid.
The Government said its concern was to ensure that all New Zealanders could get to see the games but Dr Sharples, also Maori Party co-leader, disputed that coverage was the issue.
MTS has some black spots but other arrangements including swapping to digital minimised that, he said.
"I think there's a lot of motives behind it," Dr Sharples told Radio New Zealand.
"It's about control, it's about fear of not selling their tickets and promoting their tickets and I think (they are) a little bit scared of a bit of Maori language on it."
The cup is being held in election year and that was another factor, he said.
"I think also the fact that perhaps that it mightn't come off and that would be so bad for a Government in an election year to have the rugby world cup not be broadcast suitably...
"These are all contributing factors in my mind -- a lack of confidence in Maori Television to do it."
He continued to back the MTS bid which may result in a bidding war if iwi follow through on providing additional funds.
