But the Hammers confirmed in the early hours of Friday that a move was "unable to be completed before 11pm".

Lyon subsequently accused the Premier League side of not taking the required action to complete the deal.

the Ligue 1 side criticised West Ham's "incomprehensible behaviour", adding: "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."

Lyon, who are owned by Crystal Palace co-owner John Textor's Eagle Football Holdings, said they also "reserve the right to undertake all appropriate procedures necessary to validate the transaction at a later date, and to hold West Ham responsible if necessary".

Asked about why Benrahma's move collapsed, Hammers manager David Moyes said on Friday: "It looks like there have been some problems with the paperwork at the last minute. But I only learned about it when I came off the pitch late last night."

Benrahma joined West Ham from Brentford in October 2020 and his current deal runs to 2026.

He started last season's Europa Conference League final against Fiorentina and scored the opening goal from the penalty spot in West Ham's 2-1 win.

However, the attacker has failed to find the net in 22 appearances this season and was sent off in the FA Cup replay defeat at Bristol City on 16 January. Benrahma was controversially left out of Algeria's squad for the Africa Cup of Nations tournament.

Meanwhile, West Ham had yet to confirm Pablo Fornals' £6.8m move to La Liga side Real Betis by the time the transfer window closed at 23:00 GMT on Friday.

"I think there is a chance the Pablo deal will be ratified," Moyes said at his news conference.

"I can't confirm if it will or it not at the moment though."

Moyes added: "We wanted to strengthen and we worked really hard to bring in an attacking player as well but we couldn't just quite get there."

Fornals, 27, has made 202 appearances at West Ham since his arrival from Villarreal in 2019.

But the midfielder has struggled to gain a regular starting spot this season following the arrivals of Mohammed Kudus and James Ward-Prowse in the summer, starting only started four Premier League games in 2023-24.

Although West Ham triggered a one-year option on Fornals' contract in December, it was always likely they would let him leave if the right bid was received.