Marc Emery is expected to be sentenced in late August. ((CBC))

Marijuana activist Marc Emery has pleaded guilty in a federal court in Seattle to drug distribution.

Canada's so-called Prince of Pot admitted to the charge after reaching a plea agreement with American prosecutors and is expected to receive a five-year prison term.

The 52-year-old was handed over to U.S. authorities Thursday after the federal justice minister ordered his extradition last week.

In the plea agreement, Emery admitted he operated a marijuana seed distribution business that sold to customers via his Vancouver store, mail and telephone orders.

Prosecutors say he's sold about four million marijuana seeds, and that 75 per cent of those went to American customers.

Emery will remain in a federal detention centre in Washington state until his sentencing in late August.

Emery expects to return to Canada to serve his sentence, according to his legal team.