South Sudan is joining the Chemical Weapons Convention outlawing the use of toxic arms, leaving only three nations which have not signed up to the treaty, a global watchdog said Friday.

"South Sudan has no reason to sit on the fence," top foreign ministry official Moses Akol Ajawin told the annual meeting of the Organisation for the Prohibition of Chemical Weapons (OPCW).

Juba has almost concluded the process to become the body's "newest and youngest state party", he said, according to a statement from the OPCW.

"The images of victims of chemical weapons make us all the more appreciative of the goals and objectives of OPCW," Ajawin said.

"As such, we, in South Sudan, would unreservedly like to associate ourselves with the noble goals and objectives of this great organisation."

The move was welcomed by OPCW chief Ahmet Uzumcu, who said: "Today, we are one step closer to universal membership."

A total of 192 nations have already signed up to the convention, and more than 96 percent of the planet's declared chemical weapon stockpiles have been destroyed under OPCW verification.

*This story was edited by Ahram Online.