Opposition candidates running in Venezuela's October gubernatorial elections will be investigated to make sure none was involved in violent political protests this year, the head of a new pro-government truth commission said on Wednesday.

The panel was set up earlier in the day by the constituent assembly elected last month at the behest of socialist President Nicolas Maduro. Government critics say the commission is designed to sideline the opposition and bolster the ruling party's flagging support ahead of the October vote.

Also before the assembly is a bill that would punish those who express "hate or intolerance" with up 25 years in jail. The opposition fears such a law would be used to silence criticism of a government that, according to local rights group Penal Forum is, is already holding 676 political prisoners.