The United States on Tuesday urged a peaceful solution and restraint in Kyrgyzstan as it acknowledged concerns about election conduct that have set off major protests.

"We ask that all sides refrain from violence and resolve the election dispute through peaceful means," a State Department spokesperson said.

In the latest unrest to rock a former Soviet republic, Kyrgyzstan's prime minister -- an ally of the pro-Russian president, Sooronbay Jeenbekov -- resigned Tuesday after widespead unrest by protesters who alleged mass vote-buying.

Electoral authorities cancelled the results of Sunday's polls and a new prime minister, Sadyr Japarov, was elected in an extraordinary meeting in a hotel after being freed from jail by protesters.

The State Department noted that an observer mission backed by the Organization for Security and Co-operation in Europe "found credible allegations of vote-buying that tainted the elections." 

"The Kyrgyz people must make decisions about their future, the composition of their government, and how and when elections are organized," the US spokesperson said.

"We support their sovereignty and their democratic form of government."