BEACHES on Hayling Island are to remain closed until further notice after a mysterious yellow foam was washed up.
The castor oil foam washed up along several miles of beach yesterday on the entire southern stretch of Hayling Island, as well as on beaches at East and West Wittering.
Experts say it is not dangerous to humans, but can make animals ill.
A host of agencies, including the Environment Agency and the Maritime and Coastguard Agency, descended on the island's beaches to deal with the incident.
Havant Borough Council and Chichester District Council closed the beaches yesterday afternoon as a precaution for the safety of the public.
The West Wittering Estate and Cakeham Manor also closed their beaches.
However, tests have shown the foam is made up of castor oil and is not a threat to public health.
Castor oil is a vegetable oil derived from the castor bean and has no odour or taste.
It is widely used in the food and pharmaceutical industries and is known for its medicinal use to treat constipation, arthritis and to induce childbirth in pregnant women.
The source of the oil has not yet been determined, but it is possible it came from a ship.
The authorities have warned, however, the oil can make animals ill if it is ingested.
The yellow foam was a talking-point among islanders who were bewildered as signs went up saying beaches were closed.
Daniel Ripley, 19, a barman at the Inn on The Beach, which remained open, said: 'I saw it and there was quite a lot of it.
'It looked pretty disgusting. It looked like dirty bubble bath.
'We do get foam a lot here on the beach, but not like that. It's difficult to determine where it came from.'
Mr Ripley said the foam covered up to seven-feet up the shoreline.
The local authorities said beaches would remain closed until further notice.
Further tests will be carried out on the substance before a clean-up begins.
Paul Reynolds, senior environment officer at the Environment Agency, said: 'As yet, there has been no apparent evidence of impact on wildlife.'
Havant Borough Council said its staff would begin cleaning up the oil today in order to re-open the beaches as soon as possible.