The Blues have been given permission to talk to the 27-year-old Senegal international after meeting the £7million figure stipulated in the deal he signed with the Magpies during the summer of 2011.
Ba was withdrawn from the Newcastle squad for the Barclays Premier League clash with Everton at St James' Park as a result.
A club statement said: "Newcastle United can confirm that Chelsea Football Club has made an official offer for Demba Ba which has triggered the release clause in the player's contract.
"The club has given the player permission to speak to Chelsea FC and therefore he will not be included in the squad for tonight's (Wednesday's) game against Everton."
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