The 58-year-old, from Littlehampton, was arrested shortly after 4.30pm. He is currently being questioned in custody.
Police said officers were called to the Southfields Road area after the boy told his family a man had grabbed him by the shirt while the child was on the swings at Southfields recreation ground at about 2pm on Thursday (July 30).
They added the man was dressed all in black including a balaclava covering his face apart from his eyes, with gloves and blue shoes. He then left the area and the child ran home.
Detective Sergeant Colin O’Hare said: “We have arrested a man but are continuing with our inquiries and still need the public’s help.
“I am very grateful to all those who have already contacted us but would urge anyone who knows anything but who has not yet come forward to do so.
“The park was busy with lots of other children in it at the time. I would ask parents to ask their children if they saw or heard anything and, if they did, to contact us as soon as possible.”
Anyone with any information is asked to call 101 quoting serial 756 of 30/07 or email [email protected]
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