Emissions from Canada's oil sands will likely increase faster than new technologies can be developed to curb them, says a government document cited Wednesday by public broadcaster CBC.

The memorandum to Prime Minister Stephen Harper's cabinet, marked secret, says cutting the upstream oil and gas emissions -- the nation's largest source of CO2 -- represents a "unique" challenge.

"Increasing production is expected to outpace improvements in emissions intensity and most technologies with the potential to reduce emissions have not been commercialized or technically proven," it said.

"Emissions from oil sands are projected to increase by 102 MT (million tonnes) from 2005 to 2030."

Last week Canada announced it will aim to reduce greenhouse gas emissions by 30 percent below 2005 levels by 2030.

The goal is more ambitious than Canada's previous target, but was still panned by environmental activists as lackluster.

The cabinet document outlines possible ways of dealing with the oil sands quandary, including buying international credits to offset the rise in oil sands emissions.

It also notes that future emissions targets -- after a scheduled Paris meeting in December -- may be considered in "bilateral and multilateral discussions outside of UN-sanctioned bodies."

And it urges negotiating with the United States and Mexico a continental approach to reducing oil and gas emissions.