Virgil van Dijk has called on Liverpool to continue their summer spending spree by bolstering their attack.The Reds have already spent over £290million on six new signings ahead of their Premier League title defence.GettyVan Dijk has claimed Liverpool need to bolster their attack with another signing[/caption]GettyThe Reds were beaten on penalties in the Community Shield by Crystal Palace[/caption]However, Arne Slot’s side have sold both Darwin Nunez and Luis Diaz to Al Hilal and Bayern Munich, respectively.Liverpool kicked off their campaign against Crystal Palace in the Community Shield at Wembley Stadium on Sunday and despite twice taking the lead through new signings Hugo Ekitike and Jeremie Frimpong, they were beaten 3-2 on penalties following a 2-2 draw.Following the match, Van Dijk admitted Nunez and Diaz’s exits would mean a further addition up top wouldn’t go amiss.He told talkSPORT’s Alex Crook at Wembley: “Well we just lost Darwin, he went to Saudi and we lost Lucho, obviously he went to Bayern.“I think there’s always room for an attacker in order to strengthen us so let’s see what the window brings in terms of the balance of the team.”Liverpool have been strongly linked with wantaway Newcastle striker Alexander Isak.Their previous bid, worth an initial £110million plus add-ons, was rejected by the Magpies and it’s looking increasingly likely the player will stay on Tyneside.Slot on more Liverpool signingsSlot is less convinced by the need to sign another forward as he responded to Van Dijk’s comments.The Liverpool boss said to Crook: “I think we have more than more than enough options to be good enough to win the Community Shield.GettyVan Dijk has lost two consecutive matches at Wembley[/caption]GettySlot believes his side has ‘more than enough options’ after spending over £250m this summer[/caption]“This is where I focus on myself. With the players we have we should be able to to win, to score.“That’s actually what we did as well. We scored twice and last season we only scored one against Crystal Palace, away and at home.We could only score one against them. “So my last concern at the moment is our offensive quality.“It’s more. It’s not a concern, but if I look at the amount of goals we’ve conceded in pre-season that’s not of our standard.”When asked if there’s any chance Liverpool will be signing any more defenders this summer, Slot said: “Now we’ve lost Jarell Quansah and that’s one thing. “But Unfortunately Conor Bradley, who’s a right full-back and Joe Gomez who’s a centre-back are injured. “Then Ryan Gravenberch became a dad last night, he can also play really well as a centre-back.“But if Joe is fit and Ryan is back and Wataru [Endo] can play there and the two we started today, then we’re in a good place. “So I think throughout the whole pre-season, Ali [Alisson Becker] needed to go to Brazil. Virgil was sick last week now Ryan for a very nice reason for him… but we had to miss him.“It looks as if you lack something but if everybody is there I think we have a very strong squad.”Liverpool kick off the new Premier League season at home to Bournemouth on Friday, live and exclusively on talkSPORT.