FREDERICTON - A conservation group is calling on officials to release more information about a spill of radioactive water at Atlantic Canada's only nuclear power plant.

David Coon, policy director at the Conservation Council of New Brunswick, says there are too many unanswered questions about Tuesday's spill at the Point Lepreau nuclear facility.

"They need to release the actual information on the radiation levels and exposures that might have resulted in this case," Coon said Wednesday.

"Simply giving us the volume of the spill doesn't tell us anything."

Earlier in the day, provincial Energy Minister Craig Leonard provided the legislature with an update on the incident, saying four to six litres of radioactive heavy water was spilled.

Leonard said the spill was cleaned up by staff and there are no health or environmental concerns.

"The radiation monitoring equipment is designed to sound an alarm immediately in response to even the smallest sign of radiation and that is what occurred," Leonard said.

"Staff at Point Lepreau continuously plan and prepare for exactly this kind of incident and are now doing their requisite reviews."

But Coon said the public needs to know more about what happened, such as whether the spill was the result of human error or if there are leaks.

Kathleen Duguay, a spokeswoman for Crown utility company NB Power, said the spill happened due to a leak.

"As the water is flowing through the system, there was a little leak out of a piece of equipment," Duguay said.

The heavy water system was being refilled as part of the utility's plan to restart the generating station, which has been undergoing a lengthy and expensive refit.

People were evacuated from the reactor building, but Duguay said there was no danger to staff.

The Conservation Council of New Brunswick has opposed the refurbishment of the aging Candu-6 reactor at Point Lepreau, which is intended to extend the life of the reactor by another 25 to 30 years.

The refurbishment is running three years behind schedule and $1 billion over the original $1.4 billion budget. The provincial government has asked Ottawa to cover the cost overruns to no avail.

When the project started, the reactor was expected to return to service in the fall of 2009. NB Power has since said it expects to have the power plant up and running by the fall of 2012.

Work has resumed at the plant, Leonard said.

The spill comes as NB Power seeks a five-year operating licence renewal from the Canadian Nuclear Safety Commission for the plant. The licence expires at the end of June 2012.