SAGUENAY, Que. - Premier Jean Charest says Action democratique du Quebec Leader Mario Dumont is being immature by trying to block the election of the Parti Quebecois leader to the legislature.

Charest has said he will not run a Liberal candidate against Pauline Marois in a byelection in Charlevoix riding and wants Dumont to do the same.

Dumont has said he will leave it up to the local riding executive to decide, adding there is no precedent for allowing the leader of a third-placed party to run unopposed.

"He is lacking in maturity and judgment in wanting to block Mme. Marois,'' Charest said.

It's the second time this week the premier has slammed Dumont. Charest has already gone after him for suggesting in an interview that Quebec has enough immigrants.

Marois, who became PQ leader in June, is getting a crack at a seat in the legislature after PQ member Rosaire Bertrand's decision to step aside in favour of his boss in the riding northeast of Quebec City.

The Liberals and the ADQ did not run candidates against then Parti Quebecois leader Andre Boisclair when he ran in a 2006 byelection, although the PQ was in second place at that time.

 Charest has six months to call the byelection in Charlevoix although he likely won't take that long.

"It's going to come very soon,'' he said.

Charest was in Saguenay to attend the signing of an agreement for the joint management of natural resources in the region by the Innu and the local government.

The agreement between the Montagnais council of Mashteuiatsh and the regional government of Saguenay-Lac-St-Jean sets up a regional commission to manage and protect the resources being exploited in the region.

The six regional councillors and the two aboriginals on the commission will advise the provincial government on area resource exploitation as well.