Arne Engels is undergoing a medical at West Ham United, with Celtic manager Martin O'Neill confirming the Belgium international midfielder is on the verge of departing the Scottish champions for the Premier League.

O'Neill had hoped to hold on to the 22-year-old at least until after Celtic's UEFA Champions League play-off first leg against LASK, scheduled for next Wednesday. However, West Ham's insistence that Engels be available from the opening day of the season accelerated the move.