Protest outside the Chilean embassy in London
Demonstrations have taken place internationally demanding justice for the hunger strikers, who are serving 10 years in jail for offences including arson and writing threatening letters.
Protesters highlighted the fact that the only evidence used to convict the prisoners was from "hidden" witnesses, under anti-terrorism legislation which dates back to the Pinochet dictatorship.
Chile's new left-wing President Michelle Bachelet has pledged to abolish these draconian laws, while Socialist Party Senator Alejandro Navarro expressed support for the hunger strikers last month, calling their protest "just."
Protesters in London yesterday waved traditional Mapuche flags and banners, bearing slogans such as "one dies, one thousand rise."
Passing cars beeped their horns in support, while a samba band helped to keep the energy up.
A campaign spokesman said: "Having been on hunger strike for over 50 days, the four prisoners have now started refusing water and will die soon unless the Chilean government intervenes.
"It is clear that the Mapuche will not give up defending their communities from huge corporations ruthlessly exploiting their land, even if this means the ultimate sacrifice."