Members of a First Nation community near one of the largest oil spills in Alberta's history say fumes from the leaking crude are making them sick.

A pipeline break northeast of Peace River, Alta., has leaked 28,000 barrels (nearly 4.5 million litres) of crude oil since Friday.

Lubicon Cree residents of Little Buffalo, Alta., 30 kilometres from the spill site, say they've been experiencing nausea, burning eyes and headaches since the leak began. The community closed its school and ordered children to stay at home.

"It has been four days since classes were suspended due to the noxious odours in the air," said Brian Alexander, principal of Little Buffalo School. "The children and staff at the school were disorientated, getting headaches and feeling sick to their stomachs.

"We tried to send the children outside to get fresh air as it seemed worse in the school, but when we sent them out they were getting sick as well."

The oil is now contained and about 100 workers are working to recover oil from sand and a nearby pond, said the Alberta Energy Resources Conservation Board.

Neither the ERCB nor the owner of the pipeline, Plains Midstream Canada, has spoken directly with the band, said Chief Steve Nosky.

"The ERCB is not being accountable to our community; they did not even show up to our community meeting to inform us of the unsettling situation we are dealing with," he said.

ERCB monitoring air quality

"The company is failing to provide sufficient information to us so we can ensure that the health and safety of our community is protected," said Nosky.

The ERCB is monitoring the air quality and doesn't believe the symptoms are related to the spill, said spokesman Davis Sheremata.

The school is too far away from the site to be affected, and nobody working on the spill is getting sick, he said.

The illness may be related to a separate oil and gas installation or nearby feed lots or asphalt operations, said Sheremata.

A number of beavers and waterfowl were euthanized at the spill site.

Alberta Environment Minister Rob Renner said from Medicine Hat that air monitoring equipment was activated as soon as the government learned about residents' complaints.

He said a mobile unit with capacity for extra air-quality monitoring should arrive later Wednesday. Alberta Health officials are involved with making sure residents don't suffer long-term health effects.

Even though this is Alberta's biggest crude oil leak since 1975, Renner said he had no plans to visit the site himself.

"It is under control and everyone is doing as they should be doing, and my presence there is probably not going to add any way in the way of significant added value," Renner said in a conference call with reporters.

Renner said it is too early to say whether charges will be laid against the company.

The same pipeline leaked 7,500 barrels of oil in 2006.

Alberta NDP questions timing of announcement

The incident prompted the Alberta NDP to call for an investigation into how the province inspects pipelines.

NDP environment critic Rachel Notley said the public needs to know the provincial government has enough staff to properly inspect about 400,000 kilometres of pipeline.

Notley is also alleging political interference may have been involved in the timing of when the public was told about the size of the spill.

The ERCB went public with the incident on Friday, but suggested the leak would amount to hundreds of barrels of crude oil. The latest estimate of 28,000 barrels was released on Tuesday, the day after the federal election.

"I am very concerned about the timing of that," Notley said.

"Either there's an incredible inability on the part of this government to know what's going on on the ground, environmentally ... or we have evidence of political interference, or maybe not evidence, but speculation, which is not completely unfounded."

But the ERCB's Sheremata denies information was withheld until after the election. He said the estimated size of the spill was not determined until Tuesday.

With files from The Canadian Press