Uzbek senators passed a law on Monday reducing the presidential term of office from seven to five years.
“This bill was initiated by the president...to strengthen democratic governance principles," a senate spokesman said.
Uzbekistan's autocratic leader Islam Karimov, 73, has been in power in the gas-rich Central Asian republic since 1989. Rights groups accuse the former Communist boss of serious human rights violations and silencing political dissent.
The European Union imposed an arms embargo and a travel ban against his administration after the mass killing of hundreds of unarmed protesters in the city of Andijan in May 2005.
Karimov insisted the security forces targeted Islamist militants.
The sanctions were lifted two years ago.
