Kabul, Afghanistan (CNN) -- Top U.S. officials in Afghanistan on Sunday condemned the burning of a Quran in the United States that sparked three days of protests in which more than 20 people died.
Burning the Muslim holy book "was hateful, it was intolerant and it was extremely disrespectful and again, we condemn it in the strongest manner possible," said Gen. David Petraeus, who heads the U.S.-led international forces in Afghanistan.
U.S. Ambassador Karl Eikenberry said in a statement that Americans respect the Quran "and all religious texts and deplore any action that shows disrespect to any religious faith."
"At the same time, I want to emphasize, as have many Afghan leaders, that to attack and kill innocent people in response to the deplorable act of one individual is outrageous, and an affront to human decency and dignity," Eikenbery's statement said.
NATO Ambassador Mark Sedwill of Great Britain, meanwhile, called the burning of a Quran by a small Florida church "an act of disrespect to the Muslim faith and to all peoples of faith. It does not represent the views of the peoples or governments of the alliance."
The comments came as clashes Sunday in Kandahar, Afghanistan, between police and stone-throwing demonstrators killed as many as three people, including two police officers, and injured at least 10.
Interior Ministry spokesman Zemaray Bashari said one civilian and two police officers had been killed, and that 10 were injured.
The latest clashes occurred during a protest, according to Ahmad Wali Karzai, the provincial council chief who is Afghan President Hamid Karzai's brother, and local elder Haji Abdul Malik. They said one protester died and at least a dozen people were injured.
Karzai strongly condemned the Quran burning and asked "that the U.S. Senate and House of Representatives and the U.S. president condemn this action ... in very clear words to the public," his office said in a statement.
U.S. President Barack Obama also condemned the action on Saturday, while Senate Majority Leader Harry Reid, D-Nevada, told the CBS program "Face the Nation" on Sunday that the Senate would "take a look" at the issue.
Reid stopped short of saying the Senate would vote on a resolution, adding: "As to whether we need hearings or not, I don't know."
He called the Quran burning by Pastor Terry Jones in Florida "a publicity stunt" and said: "I think people should understand the consequences of what they do under the guise of religion."
However, President Karzai's brother denied that the Kandahar protests were a result of the Quran burning.
"The protests in the last two days in Kandahar have no link to the Quran burning in U.S. at all, but were all organized by some people to loot public and government properties," Ahmad Wali Karzai told CNN, adding that he condemned the desecration of Islam's holy book.
Also Sunday, demonstrators in the city of Jalalabad, Afghanistan, protested the Quran-burning, blocking a major road that leads to the capital of Kabul, witnesses said. The Jalalabad protesters included university students.
The national assembly of clerics on Sunday condemned both the Quran-burning and the killings of civilians and United Nations staff members in the demonstrations.
At least nine people were killed and 73 injured in Kandahar on Saturday, and 12 people died Friday -- including seven U.N. employees -- when angry demonstrators stormed a U.N. compound in Mazar-e Sharif, Afghanistan.
Obama extended condolences to the families and loved ones of those killed in Mazar-e Sharif, but also decried the burning of the Quran.
"The desecration of any holy text ... is an act of extreme intolerance and bigotry," he said Saturday in a statement released by the White House. "However, to attack and kill innocent people in response is outrageous, and an affront to human decency and dignity."
Besmellah Afghanmal, a Kandahar provincial council member, said hundreds gathered Saturday in Kandahar to protest the Quran burning.
"Today the enemies of peace in Afghanistan killed and injured our people in Kandahar," said a statement from the office of the Kandahar governor.
Jones sparked international controversy last year when his Gainesville, Florida, church planned "International Burn a Quran Day" on the ninth anniversary of the September 11, 2001, attacks on the World Trade Center and the Pentagon.
Jones' church did not host a Quran burning on that day, but the Dove World Outreach Center's website announced an "International Judge the Koran Day" set for last month.
Another post on the site's blog showed an image of a burning book and read, "The event is over, the Koran was found guilty and a copy was burned inside the building."
The Mazar-e Sharif killings generated worldwide condemnation, from the U.N. Security Council to the Organization of the Islamic Conference, a 57-state group that calls itself the "collective voice of the Muslim world."
In a statement Friday, Jones called the assault on the U.N. compound "a very tragic and criminal action."
Lal Mohammad Ahmadzai, a spokesman for the police in Mazar-e Sharif, told reporters that a number of suspects "who might be the main organizers" had been arrested.
The United Nations said the seven U.N. staffers killed were four Nepalese security guards and three civilians. A U.N. source said the three civilians were from Norway, Sweden and Romania.
CNN's Nick Paton Walsh, Matiullah Mati and Tom Cohen contributed to this report