A south London hospital was partially locked down while treating a woman who had swallowed poison, police said.

Two police officers were also exposed to the substance and remain at University Hospital Croydon (formerly Mayday Hospital).

The Metropolitan Police said in a statement that police were alerted by the London Ambulance Service at 3.46am to reports that a woman had taken poison at a property in Thornton Heath.

Police said: “The woman was taken by LAS to a hospital in south London where she was found to be possibly in possession of dangerous substances.”

“Officers and London Fire Brigade attended Mayday Hospital and a security cordon and containment was set up while specialist officers inspected the item and put safety procedures in place.”

“Two officers were exposed to the substance. They remain in hospital under observation,” the statement added.

Ambulances and emergency vehicles have been allowed access to the scene and road closures have been lifted.