
In a statement, West Ham said Antonio is "currently under close supervision at a central London hospital".
The club added: At this difficult time, we kindly ask everyone to respect the privacy of Michail and his family.
The club will make no further comment this evening, but will issue a further update in due course.
The club said Antonio's road accident happened on Saturday afternoon.
West Ham face Wolves in their next match in the Premier League on Monday 200 GMT.
Antonio, 34, joined West Ham from Nottingham Forest in 2015 and has since scored 68 goals in 268 league appearances for the club.
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