* 10 percent of staffers to lose jobs, be reassigned
* Government says move needed to help cut budget deficit
* Critic says polluters will welcome news (Adds comments by government minister, opposition)
OTTAWA, Aug 4 (Reuters) - Canada's environment ministry will cut or reassign around 10 percent of its workers, unions said on Thursday, prompting fears that services like weather forecasting and environmental protection will suffer.
Officials said the move was designed to help eliminate the budget deficit. Critics said it underscored what they portray as the right-leaning Conservative government's contempt for the environment.
The cuts are part of a government plan to find C$4 billion ($4.1 billion) a year in savings by 2014-15 from an envelope of C$80 billion, or about 5 percent.
The two unions representing workers at Environment Canada said they had been told this week that 300 employees would lose their jobs while a further 450 or so would be reassigned.
Those affected include engineers, meteorologists, scientists, chemists and biologists.
William Pynn, head of the Union of Environment Workers, said meteorology, water monitoring and enforcement of regulations would suffer.
"The cuts are so massive that the support mechanism for the research that Environment Canada does ... is certainly going to be challenged," he told Reuters.
Stephen Vandervalk, president of Grain Growers of Canada, the country's largest farmer group, said farmers relied on Environment Canada for warnings about crop-damaging hailstorms and other severe weather.
Prime Minister Stephen Harper said last week that Ottawa would take "some difficult actions over the next couple of years" to eliminate a budget deficit estimated to be C$32.3 billion in 2011-12.
Treasury Board Minister Tony Clement, in overall charge of cutting government expenditures, told reporters that "Environment Canada is open for business, they're doing their job, and they want to do it more efficiently".
Unions fear Ottawa will slash the federal civil service to meet Harper's target of returning to the black by 2014-15.
"This was a bit shocking and surprising and we're really sad. This is really going to throw the department into a bit of turmoil," said Gary Corbett, president of the Professional Institute of the Public Service of Canada.
Green critics say the government -- which has strong political support in the oil-rich western province of Alberta -- is far too close to the oil and gas industry.
"This is not about the deficit. This is about a blatant disregard for need to protect our natural heritage," said John Bennett, the executive director of Sierra Club Canada.
"It will give the polluters what they want, a toothless Environment Canada with no scientific or enforcement capability," he told Reuters.
Environment Minister Peter Kent raised eyebrows in January when he referred to oil from northern Alberta's tar sands as "ethical". Green groups say exploiting the tar sands produces high amounts of greenhouse gases and other toxins.
($1=$0.98 Canadian) (Reporting by David Ljunggren)