Nobel laureate Egyptian-American chemist Ahmed Zewail died Tuesday of an unknown cause.

"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," Zewail's spokesperson Sherif Foad said, according to Reuters .

Zewail was awarded the Nobel Prize in Chemistry in 1999 for his work in femtochemistry, the study of chemical reactions that happen in short timescales.

At that time, Zewail was the third Egyptian national to receive a Nobel Prize, following Anwar Al-Sadat in 1978 and Naguib Mahfouz in 1988. He was also the first Arab to win a science Nobel, with most Arab laureates having won the Peace Prize.

Born in Damanhur, 160 km northwest of Cairo, Zewail studied at Alexandria University. He later moved to the United States to complete his doctorate at the University of Pennsylvania.

In 1976, Zewail became a member of the California Institute of Technology (Caltech) and a professor of chemistry and physics at the University of California at Berkeley.

Zewail was a science and technology participant in U.S. President Barack Obama's Presidential Council of Advisors on Science and Technology, a group composed of leading scientists and engineers helping with policies in relevant fields.

He was also among the first U.S. science envoys to the Middle East in 2010, alongside Elias Zerhouni and Bruce Alberts.

Throughout his lifetime, Zewail published 600 scientific articles and 16 books, a legacy that will remain with us in his absence.

A four-time Lebanese sports champion is calling foul on the country’s selection of Olympics representatives this year.

“I will not be [in] Rio this summer to represent Lebanon … I did everything I could to go to the Olympics … but politics is stronger than sport performance,” member of Lebanon’s national swimming team Adam Allouche wrote on his Facebook page.

Allouche achieved the highest number of swimming credentials, known as FINA points, among national athletes vying for a spot at the 50-meter men’s freestyle but was passed over for Anthony Barbar. Lebanon’s Swimming Federation claims that Allouche only exceeded Barbar’s qualifications after their selections were submitted.

Yet, by the Federation’s own admission, the list of Olympics representatives were sent weeks ahead of time, and Berber’s status changed well before the deadline for modifications. The Federation decided against informing the Olympics about the change in order to “avoid a legal clash with Berber.”

The Olympics Committee charged with aquatics (FINA) told Allouche that the selections list would have been amended, but only with official notification from Lebanon.

Jordanian swimmer Khader Baqlah was in a similar predicament, having scored the needed FINA points only after selections were submitted. But Jordan’s committee modified their list, and Baqlah will now compete in the Olympics 50-meter men’s freestyle.

“I lost confidence in the Lebanese Swimming Federation. It’s a big mistake from them … they don’t realise that the Olympics represent a lot of hard work for us,” Allouche told StepFeed.

Allouche lives and swims in Paris, but has been part of Lebanon’s national swimming team since 2013. He holds four national records in swimming and competed in the Mediterranean Games in Mersin, Turkey in 2013.

“My next step? I don’t know. Like you can see, nothing is sure here. I want to be at the next World Championships but [it] isn’t me or my performance that decide,” said Allouche.

“For now, I need a break. It will be hard to watch the Olympics on TV but I will follow the performances of the Lebanese delegation. I wish them all good luck.”