The boy is believed to come from the local area and has not yet been named. He is said to have been in the sea just after 4pm this afternoon with a friend when he disappeared.
Sussex Police began searching their area assisted by the local coastguard and other emergency services around the West Beach area of Newhaven.
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Monday's weather forecast for the east of the region
Monday's weather forecast for the west of the region
Monday's weather for the east of the region