Peterborough United have signed striker Britt Assombalonga from Watford for an undisclosed fee.

The 20-year-old, who scored 20 goals on loan at Southend United last season, has penned a four-year deal with the League One club.

"Everyone is aware we have been looking for a striker and this is the one that we have been after," United manager Darren Ferguson told the club's official website.

"We thought initially it was going to be a loan, but the chairman has come up with the money and that is fantastic for me.

"He has once again backed me. It was a position we needed to fill."

Assombalonga is expected to be part of the Peterborough squad for Saturday's League One opener at home to Swindon Town.