Aboriginal Land Council of Tasmania chairman Michael Mansell told a parliamentary committee on Monday there should be designated seats whether or not numbers in the lower house grew from 25 seats to 35.

He said even if every Aboriginal person in an electoral division was to vote for an independent Aboriginal representative, there would not be enough votes to get that candidate into Parliament.

"The dices are heavily loaded against us," Mr Mansell said.

"You've got this debate going on federally about a voice to the Parliament - what about a voice in the Parliament?"

He said designated Aboriginal seats was the only way to ensure the Tasmanian Parliament was truly representative and democratic.

Mr Mansell said an Aboriginal person elected to Parliament as part of a party would be constrained by party solidarity and might not be able to act as effectively on issues dear to their community as they otherwise would as an independent.

Voting analyst Kevin Bonham said a mix of two statewide seats amongst the current system of seats could be problematic although he agreed with the motive of the cause. "In a reasonably balanced Parliament, these seats would become very powerful," he said.

"Due to the number of people involved, this could become disproportionate."

Dr Bonham said there were good arguments as to why House of Assembly numbers should be increased.

He said a 25-member house meant there was a limited number of backbenchers which led to a problem in replacing ministers.

As for ministers, he said a small cabinet made up of ministers with several portfolios meant there would be a greater chance of conflicts of interest. Dr Bonham said the system of five seats per electorate meant there could be issues for parties in the event of a recount by not having a candidate to take a particular seat.