Police are investigating reports of a man sexually assaulting a 13-year-old boy on a bus.

The incident happened on Saturday, June 8 when a boy was boarding a bus from his home in Great Yarmouth to meet his friends in Norwich.

He sat upstairs on the X11 First Bus and was the only person on the top deck until a man got on and is said to have sat next to the boy.

The man is then reported to have continually touched the boy's leg inside his thigh and even attempted to kiss the boy before he exited the bus at Acle.

The boy remained on the bus to see his friends in Norwich.

The boy was travelling from Yarmouth to Norwich to see his friendsThe boy was travelling from Yarmouth to Norwich to see his friends (Image: First Bus)

His mum said he was left petrified after the incident and did not report it until three weeks after it happened when he told a teacher at his school.

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As soon as the boy's mother was told she immediately reported it to the police and she says she is unhappy with how the police have dealt with the incident.

In response Norfolk Police stated the "incident is under investigation".

First Bus has been approached for comment.