Nobel Prize-winning Egyptian chemist Ahmed Zewail has died in the United States, his spokesman has told Egyptian state TV.
Zewail, who was 70, won the prize in 1999 for pioneering work in femtochemistry, which studies chemical reactions in ultra-short timescales.
"The cause of death is unknown ... whether it is cancer or something else ... his doctor said his condition was stable the last time I called him last week," spokesman Sherif Foad said on Tuesday.
Zewail was born in the city of Damanhur, studied at Alexandria University and later moved to the US where he and earned his PhD at the University of Pennsylvania in Philadelphia.
