TORONTO (Reuters) - A group of Canadian refugee lawyers is taking the government to court over a recent immigration ruling, calling it unfair to Nigerian asylum seekers who have streamed across the border from the United States in large numbers over the past 18 months.

FILE PHOTO: Nigerian refugee claimants Abimbola Ogunyemi (L) and Esther Ogunyemi (R) shop for groceries with their four-year-old daughter Nifemi at the Welcome Hall Mission food bank in Montreal, Quebec, Canada, February 13, 2018. Picture taken February 13, 2018. REUTERS/Chris Wattie/File Photo

The legal challenge from the Canadian Association of Refugee Lawyers was prompted by the decision to designate as precedent-setting a May ruling by Canada’s Immigration and Refugee Board (IRB) rejecting the asylum claim of a Nigerian woman who fled her homeland to escape the practice of female genital mutilation.

A tribunal in the IRB’s appeals division ruled that the woman failed to qualify for asylum because she could have sought refuge in the large Nigerian cities of Ibadan or Port Harcourt, away from her rural family home.

Last month, in the wake of the appeal division ruling, the IRB said the woman’s case should be used as a “jurisprudential guide” or legal precedent in considering all future Nigerian asylum cases.

The IRB has made similar decisions in cases involving migrants from China, India and Pakistan.

The Canadian Association of Refugee Lawyers said Nigerians would now likely face a higher bar to gain asylum status than they did in the past.

“It’s very problematic,” Lorne Waldman, an attorney with the association told Reuters. “It enhances the evidentiary burden on claimants from Nigeria in a way that I say is unfair.”

Canada is struggling to cope with a wave of asylum seekers, with more than 30,000 having illegally walked across the Canada-U.S. border since January 2017, according to government figures.

About 10,000 of those who crossed are Nigerian. Their acceptance rate as of June was about 33 percent, below the average of 47 percent for all those who crossed the border illegally, according to data from the IRB.

The Association of Refugee Lawyers filed a request for a judicial review of the new guideline in federal court in Toronto last month. If successful, it could seek a court order blocking the new evidentiary requirements for Nigerians, potentially covering Chinese, Indian and Pakistani asylum seekers as well.

An IRB spokeswoman said in an email that the purpose of the Nigeria guideline was to ensure “consistency and efficiency in decision-making” about refugee claims from what she described as a “major source country.”

It has already cost some claimants their chance at refugee status, according to lawyers.

Last week, an IRB tribunal member ruled against granting asylum to a Nigerian man and his family on grounds that there were safe places for them to live in Nigeria, said his lawyer Anne Castagner.

The man, who asked to be identified only as Samson out of fear for his family’s safety, said he was a prominent property developer in Nigeria when he began to be targeted by what he suspects were rival developers.

He and his family were attacked repeatedly, according to his asylum claim. They moved to another city but were pursued by the same people, he said, so they fled to the United States and then on across the border into Canada.

There was no safe flight alternative in Nigeria, he said.

“I can’t imagine having to go back to a country where our lives are not safe ... They should send me back, but not the kids.”

Castagner is preparing to appeal Samson’s case but said she worries about upcoming cases.

“I don’t think the real refugees should suffer from the fact that we have a lot of Nigerians coming in,” she said.