The man was arrested at the scene in Rainham
Police were called at around 11pm on Friday, 2 June after a woman, aged in her 30s, was found injured inside a property in Betterton Road.
The victim was taken to hospital by the London Ambulance Service in a critical condition.
The man, who police believe knew the victim, was arrested at the scene in connection with the incident.
He remains in custody.
Anyone with information that may assist police is asked to call 101, ref 8344/02jun.
To remain anonymous, please contact Crimestoppers.
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Tags: Havering, Rainham, Metropolitan Police, London Ambulance Service