West Ham United will know within the next 24 hours whether they have signed Sebastien Haller for a club record fee of £45million.

Negotiations hit an impasse on Tuesday afternoon after an attempt by the French striker’s lawyer to change the terms of his four-year contract.

This has caused a great deal of frustration at West Ham who believed they had agreed a deal not just with Haller’s club, Eintracht Frankfurt, but with the 25-year-old himself over his personal terms.

Haller flew into London for a medical and with West Ham hoping to quickly push through a deal, knowing that other clubs, including one competing in the Champions League, were interested in the forward.

West Ham do remain confident that the move will still happen, given the fee they are offering and Haller’s desire to join them, but there is annoyance at the hold up which has cast some doubt.

It would be particularly frustrating given Frankfurt have officially confirmed the deal has been agreed but, as of last night, negotiations were continuing with Haller’s representatives.

Haller, who joined the Frankfurt from Dutch club Utrecht and was a France Under-21 international, is 6ft 3in and is regarded as a traditional number nine and helped his team reach the Europa League semi-finals where they were knocked out by Chelsea.

Although attention has focussed on the exploits of his now former strike partner, Luka Jovic, who has joined Real Madrid, Haller actually out-scored him in the Bundesliga last season. Haller scored 15 goals with nine assists in just 23 starts for Frankfurt in the league last season and 33 goals in 77 appearances overall for the club.

Signing Haller would be a significant boost for West Ham who have been in the market for a centre-forward with Javier Hernandez having struggled to impress and with Andy Carroll allowed to leave after his contract expired – although he is back training with the club. Lucas Perez has also left West Ham after failing to impress after his move from Arsenal.

The sale of Marko Arnautovic to Chinese club Shanghai SIPG for £22.4million has also raised the pressure on adding to manager Manuel Pellegrini’s forward options with West Ham also missing out on Maxi Gomez who joined Valencia despite it looking at one stage that the deal might be hijacked.

The fee for Haller is a club record, beating the £35million, rising to £42million with add-ons, that they paid Lazio to sign Brazilian winger Felipe Anderson last summer.

If Haller signs he will become the third player to move to West Ham this summer following the arrival of midfielder Pablo Fornals and goalkeeper Roberto.

Meanwhile West Ham have sold defender Sam Byram to newly-promoted Norwich City for just £750,000.