Marc Emery, Canada's self-proclaimed Prince of Pot, has pleaded guilty to conspiracy to manufacture marijuana in a Seattle court.

The 52-year-old is expected to receive a five-year prison term after reaching a plea agreement with American prosecutors.

In a release, U.S. attorney Jenny Durkan said Emery had "made millions of dollars promoting and facilitating marijuana grows in the United States with no regard for the age or criminal activities of his customers."

"A five year prison term will hold Emery accountable for his choice to ignore the law," she said.

Emery's co-accused, Michelle Rainey and Gregory Keith Williams, were sentenced to two years of probation as part of Emery's plea agreement.

Prosecutors say Emery has sold about four million pot seeds through his Cannabis Culture magazine and website. Emery, a longtime advocate of pot legalization, has said he is proud of his business and has no regrets.

One of his lawyers, Kirk Tousaw, said Emery will apply to serve his sentence in a Canadian prison.

"The United States has already agreed to support Mr. Emery's treaty transfer back to Canada to serve his sentence here," Tousaw said.

Emery was extradited last Thursday to the U.S. His wife Jodie received an email from him over the weekend from prison, which she posted on her blog.

In it, Emery calls prison food "dubious," but sounds generally positive and speaks of making a friend who he plays dominoes with.

"Everyone is here for drugs that I have spoken to so far, everyone," it reads. "A lot of failed urine tests, breaches of probation, trafficking, etc. It's almost all drugs."

Sentencing is scheduled for 1:30 p.m. on August 27. Until then, Emery will remain at the Federal Detention Center at SeaTac, Washington.

Emery previously spent three months in Saskatoon Correctional Centre, and has been arrested more than a dozen times in Canada.

He has also run for office numerous times with the B.C. Marijuana Party.

With files from The Canadian Press