In a letter sent to Attawapiskat Chief Theresa Spence on Christmas Day, Duncan said he was worried about the leader's well-being and urged her to end her protest.
Spence has been on a hunger strike since Dec. 11 to focus public attention on aboriginal issues, and has been living in a teepee on an island in the Ottawa River that many aboriginals consider to be sacred land.
She is seeking a meeting with the prime minister, the governor general and First Nations leaders to discuss the government's relationship with First Nations.
Duncan's letter said Spence had been unresponsive to his offer of meeting with her or speaking to her by phone.
It also said Aboriginal Affairs was prepared to set up a working group between federal and First Nations representatives to discuss treaty and rights issues between Ottawa and aboriginal governments.
"I remain concerned about your health and hope that you will accept my offer to speak about how we might move forward with improving the treaty relationship," Duncan wrote.
"It is unfortunate that you are unwilling to speak with me about the issues you have raised publicly."
Duncan's letter came a day after Conservative Senator Patrick Brazeau, who is Algonquin, tried unsuccessfully to meet with Spence.
Brazeau posted an account on Twitter of his efforts to meet Spence on Monday, saying he was first told she needed time to prepare to see him but then that she wouldn't see him at all.
"Not sure if Chief Spence's advisors made the recommendation not to meet but regardless, I respect her decision," Brazeau wrote.
Spence's hunger strike helped spark the national Idle No More movement, which in turn has spawned several protests and demonstrations — including an ongoing Sarnia, Ont., rail blockade.
Many of the protests are focused on denouncing the Harper government’s omnibus Bill C-45, which demonstrators claim eliminates treaty and aboriginal rights set out in the Constitution.
The Conservatives maintain that they are taking strong action to address aboriginal concerns.
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