Four people have been killed in the Afghan city of Kandahar during a demonstration against the burning of a Koran in the United States.
It followed a protest over the same issue in the northern city of Mazar-i Sharif on Friday left 14 people dead, including seven UN workers.
The BBC reports it was the worst attack on the UN mission in Afghanistan since the international invasion in 2001.
Separately, three insurgents were killed when they attacked a NATO base. They were stopped before they could enter the compound.
Hundreds of people joined the demonstrations in Kandahar on Saturday and a BBC correspondent says the city is under lockdown.
United Nations Secretary General Ban Ki-Moon has condemned the violence in Mazar-i Sharif as "outrageous and cowardly".
Afghan president Hamid Karzai said it was inhumane and against Islamic and Afghan values.
The Taliban has denied it carried out the attack.
Police say that 27 people have been arrested following the demonstration in Mazar-i Sharif.
Officials said clerics had urged people to protest over last month's burning of a copy of the Koran in the presence of US pastor Terry Jones.
He has denied responsibility for the violence in Afghanistan.
Witnesses said the protest began peacefully but suddenly turned violent.
Several demonstrators were killed by guards, who were then overpowered by the mob.
On 20 March, Pastor Wayne Sapp set light to a copy of the Koran at a church in Florida.
The burning took place under the supervision of Pastor Jones, who last year drew condemnation over his aborted plan to burn copies of the Koran on the anniversary of the 9/11 attacks.
