Chelsea have confirmed that assistant first-team coach Steve Clarke has handed in his resignation at Stamford Bridge, with West Ham seeking to recruit the Scotsman.
Clarke is being lined up as assistant manager to new Hammers boss Gianfranco Zola, but the Blues have so far refused to rubber-stamp any deal.
A short statement from Chelsea read: "Chelsea Football Club can confirm that West Ham United have made an approach with regards to talking to Steve Clarke. They have not been given permission to talk to him.
"Steve Clarke has tendered his resignation as assistant first-team coach. We have not accepted his resignation and talks are continuing."
Forty-five-year-old Clarke was number two to Jose Mourinho during the Portuguese's reign at Stamford Bridge, before becoming assistant first-team coach under Avram Grant last season.
He had previously spent more than a decade as a player with the Blues, making well over 400 appearances for the club in all competitions.