Supporters of WikiLeaks co-founder Julian Assange say his health is deteriorating behind bars.

This follows a London Court ruling the Australian journalist can be extradited to the United States where he faces spying charges.

Tauranga-based lawyer Craig Tuck says Assange is being punished for speaking truth to power.

Greg Barns is a senior counsel adviser of the Assange campaign and member of the New Zealand Bar, he talks to Māni Dunlop.