The Hammers were also in the market for a high-profile centre-forward in the last two transfer windows, but they are yet to capture a player who fits that description.
"It's clear to most fans that we are desperate for centre-forwards. Andy Carroll is injury-prone as we know, we have had an injury problem with [Diafra] Sakho and we have just got to bring in centre-forwards. We have got to find the money. Without strikers, you struggle in the Premier League. You struggle in any division because strikers are your key players," he told talkSPORT.
"You have to spend your money wisely but it must be on strikers, particularly strikers that have had experience with Premier League football - the very best we can afford. We have tried the route of going overseas to bring in players - that hasn't worked. We had a very difficult season because players we brought in from Europe didn't make the grade and we paid the price. We struggled.
"We were actually flirting for some time with relegation because we couldn't score goals. That is why we have got to bring in players with Premier League experience and that is what we are working on now. David Sullivan is working day and night in an effort to solve this problem."
West Ham have also been linked with Jack Wilshere following his loan spell at Bournemouth last season.