A coconut left inside a coffin in Bolton, Manchester, 'sent fear' through crematorium staff when it exploded - and mourners have now been urged not to 'slip' items in with the deceased.
Bolton Council asked grieving family members and friends to stick to crematorium rules and to not add any items into coffins that could become dangerous.
Donna Ball, Assistant Director of Community Services, said a 'hell of an explosion can sometimes occur'.
'We have seen a rise in things like e-cigarettes, and mobile phones. Mobile phones in particular are a real issue for us'.
Ms Ball told the BBC: 'Usually the funeral director will pick them up but sometimes things are slid inside peoples' pockets and they are just not picked up during the process, then when they go through the cremation process a hell of an explosion can sometimes occur'.
Louise Walch-Grognet, of Fred Hamer Funeral Services, in Bolton, said they ask mourners to not place certain items with the deceased in an 'honest and open way and it is usually okay'.
But the funeral director still has to check the coffins after a service as relatives try to sneak items in.
'They're not thinking at that moment about protecting the staff at the crematorium,' she added.
Ms Walch-Grognet said that during her 17-years in the occupation 'it has changed so much as more people request to have mobile phones and e-cigarettes left inside the coffin'.
These belongings cannot be placed with the deceased and are given back to the grieving family.
On one occasion the funeral director was even asked if a spare set of underwear could be placed inside the coffin.
Other items of concern include TV remotes, lighters and bottles of alcohol.