Slaven Bilic rejected Grzegorz Krychowiak and Renato Sanches, says West Ham chairman David Sullivan

Co-chairman David Sullivan has explained West Ham United's failure to complete a late club-record transfer for Sporting Lisbon midfielder William Carvalho and sensationally claimed that under-fire manager Slaven Bilic rejected the opportunity to sign both Grzegorz Krychowiak and Renato Sanches.

The Hammers were said to be confident of adding Carvalho to a summer haul comprised of Joe Hart, Pablo Zabaleta, Marko Arnautovic, Javier "Chicharito" Hernandez and Sead Haksabanovic, but talks broke down amid reports from Sky Sports that Sporting would not lower their £40m ($51.8m) valuation having apparently received an opening bid of €30m that included a further €10m in performance-related add-ons.

However, Sullivan now claims that the Primeira Liga leaders actually returned to accept that initial offer on Thursday (31 August) as the clock ticked down towards the deadline, but left West Ham with no adequate time frame to conduct the necessary medical.

It had also been claimed that the club had reservations regarding Carvalho's fitness and understandably they were not willing to take the risk of signing him without such an assessment having taken place.

"Overall Slaven is happy with the business we have done during the summer transfer window. We received the manager's wish-list before the window opened and we have managed to get the top four players on it," Sullivan told West Ham's official website late on Friday evening.

"It is no secret that we made a club-record bid for Sporting Lisbon's William Carvalho but unfortunately that offer was rejected a couple of weeks ago. Late last night Sporting Lisbon made contact to accept the original offer, but unfortunately it was just too late in the day, and we simply did not have enough time to put the player through a medical.

"We were not prepared, as a club, to buy a player for that amount of money without him having gone through adequate medical checks."

West Bromwich Albion and Swansea City pulled off two of the most surprising and impressive deals of the entire window on deadline day, with the Baggies loaning former Sevilla star Krychowiak from Paris Saint-Germain and Paul Clement utilising his close relationship with Carlo Ancelotti to secure the arrival of Bayern Munich's highly sought-after midfield talent Sanches.

West Ham could have signed either player before those respective moves, according to Sullivan, only for Bilic to declare himself satisfied with his options despite the collapse of that deal for Carvalho.

"Grzegorz Krychowiak and Renato Sanches were both offered to the manager before their switches elsewhere, but he told us that he is happy with the squad he has," he added. "As a board we are behind Slaven, and he believes he has the tools to turn around our form and rectify our disappointing start to the season."

Bilic already came under severe pressure last season and has yet to be offered an extension to his current contract, which is due to expire in less than 11 months time. Speculation regarding his possible dismissal has ramped up again of late after three successive defeats - including a truly listless 3-0 loss to newly-promoted Newcastle United - left West Ham rooted to the foot of the Premier League table with an alarming goal difference of -8.