Lyon have launched a stinging attack on West Ham after Said Benrahma’s transfer to the Ligue 1 club fell through on deadline day.

Algeria winger Benrahma underwent a medical in France on Thursday afternoon ahead of a proposed loan switch and permanent deal in the summer.

However, Lyon say West Ham failed to complete the transfer ahead of the 11pm deadline, accusing the Premier League club of a lack of respect and threatened to take further action.

A statement read: “Olympique Lyonnais deeply regrets the failure of the transfer of Saïd Benrahma, for reasons beyond its control, and questions the behaviour of West Ham which did not succeed in finalising the required administrative procedures despite all the agreements concluded.

“Olympique Lyonnais were delighted to welcome Saïd Benrahma to Lyon this Thursday to finalise his transfer from West Ham. The two clubs had signed a temporary transfer agreement, and Olympique Lyonnais had obtained approval to allow the transfer to take place smoothly and transparently.

“However, at the start of the evening, while Olympique Lyonnais had entered all the administrative data on the dedicated FIFA platform (FIFA TMS), West Ham had never launched the slightest technical procedure on its part, despite the repeated reminders from the OL and continuous mutual telephone communication.

“In the absence of this reciprocal action on the part of the English club and following this incomprehensible behaviour, raising questions, the international transfer certificate could not be requested before closing time.

“Olympique Lyonnais deeply regrets this situation and this decision, demonstrating a profound lack of respect on the part of West Ham towards the institution and the player.

“The club reserves the right to undertake all appropriate procedures necessary to validate the transaction at a later date, and to hold West Ham responsible if necessary.”

While Lyon were attempting to finalise the deal, West Ham were labouring to a 1-1 draw at home to Bournemouth, notably without a left winger.

A West Ham spokesperson later said: “West Ham United can confirm that the deadline day deal for Said Benrahma to join Olympique Lyonnais was not concluded ahead of the deadline, with a deal unable to be completed before 11pm,”

Benrahma could, theoretically, be back in David Moyes’ squad for Sunday’s trip to Manchester United.