The news follows a ratings downgrade Tuesday and a profit warning last week that saw Finland-based Nokia's shares to slump to a 13-year low, as the world's largest handset maker by sales warned it may not make a profit in the second quarter.
"Rich Green is taking a medical leave [of] absence. During this time Henry Tirri, head of Nokia Research Centre, will be the acting CTO," The Wall Street Journal quoted Nokia spokesman Tomi Kuuppelomaki as saying.
Kuuppelomaki further said, "There was no specific timetable for Green's return."
However, Finnish newspapers are saying that he was unlikely to return because of disagreements over the strategy of the struggling mobile phone company.
Nokia's failure to keep pace in the high-end handset market with rivals, including Apple's iPhone and Google's Android, saw it abandon its Symbian platform for smartphones in February in favour of a partnership with Microsoft and its Windows Phone software as it strives to regain lost market share.
But the first Windows phones won't be shipped until at least the fourth quarter, and Nokia's market share has continued to fall as consumers favour rival operating platforms.
Green, 55 year, joined Nokia in 2010 under former CEO Olli-Pekka Kallasvuo. Before joining Nokia, Green was executive vice president of Sun Microsystems' software division.
According to the publication, Tirri and Green were not immediately available to comment.
Image: Richard Green