Ceremonies at a California cemetery marked the mass murders and suicides 40 years ago of 900 Americans orchestrated by the Reverend Jim Jones at a jungle settlement in Guyana, South America.

The remains of more than 400 Jonestown victims are buried at Evergreen Cemetery in Oakland.

Jones’ adopted son Jim Jones Jr and other former Peoples Temple members conducted a service on Sunday at granite slabs bearing names of all 918 who died in Guyana on November 18 1978.

Jonestown 40 Years Later
File photo shows the Peoples Temple compound, after bodies were removed, in Jonestown, Guyana (AP)

Minister Jynona Norwood, who lost 27 relatives, separately unveiled a portable memorial wall to honour more than 300 children and other victims.

She left off the names of Jones and those she says assisted him.

Both memorials list California Congressman Leo Ryan, three journalists and a church defector killed by temple gunmen at an airstrip.