Premier David Alward says he plans to support his deputy premier while the RCMP investigates an allegation that he interfered in a police investigation involving his brother.

The explosive allegation was made in the New Brunswick legislature Tuesday afternoon and has the Liberals calling for Paul Robichaud's resignation.

RCMP are looking into an anonymous tip that Robichaud, who also serves as New Brunswick's economic development minister, tried to prevent his brother from being charged with an aquaculture infraction.

The tip came in the form of an anonymous letter that has been circulating throughout political circles and landed in the laps of the Liberals, who then passed it onto the RCMP.

"We have been advised by the RCMP today that there will be a criminal investigation into this matter," said Opposition Leader Victor Boudreau in the legislature Tuesday. "In light of this, will the premier ask the deputy premier to step down pending the outcome of this investigation?"

"I'm certainly not aware of this situation and I would be pleased to take it under advisement," Premier David Alward responded yesterday.

Today Alward said he would support Robichaud while the RCMP reviews the letter.

The Crown says a man named Donat Robichaud has been charged with practising aquaculture on an unpermitted site, under the Aquaculture Act.

Robichaud does have a brother named Donat, but there is no confirmation that the person charged is his brother.

According to a letter handed out by the Liberals, the RCMP say an investigator will be assigned to look into the allegations; for the Grits, that is enough to demand Robichaud's resignation.

"When the deputy premier was in opposition he was very vocal in a somewhat similar situation, where he felt that anybody under any type of investigation like this should have to resign," said Boudreau.

Alward says he will report back to the legislature about the allegation.

"This is the first we've heard of these allegations," says New Brunswick Justice Minister Marie-Claude Blais. "They are allegations and we are establishing that there is a process."

Robichaud isn't commenting on the case.

With files from CTV Atlantic's Nick Moore