Brentford have turned down an improved offer from Newcastle United for forward Yoane Wissa, according to multiple reports. The proposal was structured at £35 million up-front with a further £5 million in performance-related bonuses, taking the potential value to £40 million. It is the second bid Newcastle have lodged for the 28-year-old Congo international this week, and the London club are insisting they have no obligation to sell. Wissa, who scored 12 Premier League goals last season, is understood to be pushing for the move and believes he had an informal agreement with Brentford to consider offers this summer. Newcastle are looking to reinforce their attacking options as uncertainty grows over the future of Alexander Isak. Isak, who scored 27 goals in all competitions last term, posted on Instagram that "promises were broken" and that "the relationship can’t continue," escalating a summer-long standoff after the club rejected a reported £110 million offer from Liverpool. Newcastle responded by saying no assurances had been given about a transfer, and club legend Alan Shearer criticised the striker’s public statement, calling the situation an "absolute mess."