At least 86 people have been killed and more than 1,100 have been wounded in the clashes between ethnic Uzbeks and Kyrgyz.
The interim government said the state of emergency was extended from the city of Osh "in connection with the ongoing clashes taking place in Jalalabad, in the interest of public safety and for the speedy normalisation and establishment of public order.”
A 24-hour curfew has been put in place in Osh and all military reservists aged between 18 and 50 have also been called into action
Rights group Amnesty International called on authorities to protect citizens "of Uzbek origin who have been targeted during the violence". It also urged neighbouring Uzbekistan to take in refugees, saying between 2,000-6,000 people had fled to the border.
Uzbekistan voiced "extreme alarm" at the violence, while the United States, which has an air base outside the capital Bishkek, also expressed concern.
"The United States is closely monitoring developments in the Kyrgyz republic and calls for a rapid restoration of peace and public order," State Department spokesman Philip Crowley said on Saturday.