Bruce has already signed striker Frazier Campbell from Manchester United this summer for a fee of £3.5m and has also brought in Paraguay defender Paulo da Silva.
The former Wigan boss, backed by millionaire owner Ellis Short, has funds available to further strengthen his squad and revealed there could be plenty more arrivals at the Stadium of Light before the start of the new season.
"We have a number of irons in the fire," added Bruce.
"We'll be looking to make several additions to our squad in the coming weeks."
Fulham were also reportedly interested in signing Crouch after they agreed to sell striker Bobby Zamora to Hull City for £5m.
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