West Ham have accused Dimitri Payet of displaying a lack of “commitment and respect”.
The allegation was made on Monday after the Hammers agreed that the France international rejoins his former club Marseille.
The club’s chairman, David Sullivan, said although he wanted Payet to stay with them, Slaven Bilic approved the sale in “the interests of squad unity”.
The 29-year-old, however, said he needed to “return to his roots” at his former club.
The offer was reported to be £1 million higher than an initial £19 million bid.
Payet joined West Ham from Marseille for £10.7 million in June 2015 and signed a new contract in February 2016 to tie him to the English side till the summer of 2021.