As many as 100 million spare house keys are currently in circulation in the UK, according to new research.
A study carried out by Sainsbury's revealed that millions of householders have either lost spare sets of keys of forgotten to retrieve them from neighbours and tradesmen.
Commenting on the findings, Sainsbury's spokesman Neil Laird said: "Although it's sensible and often necessary to leave a spare set of keys with a trusted person to gain access to your property, it's concerning to see just how many homeowners have completely lost track of who could have access to their home."
Mr Laird warned homeowners that failure to take care of keys could potentially invalidate insurance policies and put families at risk.
Those who are unaware of where their spare keys are located are advised to take the "safest measure" and have locks changed.
According to the BBC, homeowners should shop around for insurance and find the policy that best provides the level of cover they require.
Homeowners can take steps to reduce the risk of fire and burglary by fitting secure locks to doors and windows and ensuring that smoke alarms are fitted.
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