* Ametsreiter to leave end-July
* Ametsreiter says will likely talk about new job next week
* Contract was due to end in Dec. 2016 with extension option
* Telekom Austria shares down around 4 pct (Adds Ametsreiter comments)
VIENNA, June 15 (Reuters) - Telekom Austria Chief Executive Hannes Ametsreiter unexpectedly quit on Monday to leave the unit of Mexican tycoon Carlos Slim's America Movil at the end of July to move to a new job which he declined to name.
One source said Ametsreiter had got an offer for another position "which was not to be turned down".
"I expect that by the end of next week I will tell you where my future job will be," a smiling Ametsreiter said at a corporate event on Monday evening.
Two sources with knowledge of the matter said the move came as a surprise. Ametsreiter's contract was set to run out at the end of 2016 and had an extension option until 2018. He had been at the helm of the company since 2009.
Shares in Telekom Austria hit their lowest since February, closing down 3.9 percent.
Slim, who owns around 60 percent of the group since last year, has said he wants to use Telekom Austria as a base for further expansion into central and eastern Europe. Austria's state holding company OBIB owns 28.4 percent.
Slim had introduced Alejandro Plater as Telekom Austria's new chief operating officer in March. Should no successor be appointed by the end of July, Plater as deputy CEO would take over in the interim period.
Telekom Austria's supervisory board will discuss the question of Ametsreiter's successor on July 24, according to a source in the body, who also said Ametsreiter decided to leave voluntarily and not due to pressure from America Movil. (Reporting By Angelika Gruber, Alexandra Schwarz-Goerlich, Shadia Nasralla; Editing by Georgina Prodhan and David Evans)