Afghan President Hamid Karzai has lambasted NATO forces over a series of recent airstrikes that reportedly caused dozens of civilian casualties, saying that such attacks could threaten a U.S.-Afghan strategic agreement.

The airstrikes were carried out beginning on Sunday across four provinces, and killed or injured "dozens of Afghan civilians — including women and children," according to a statement from the Afghan presidential palace.

Karzai summoned U.S. Ambassador Ryan Crocker and the commander of the International Security Assistance Force, Gen. John Allen, on Monday to ask for an explanation of the incidents, CNN reported.

Karzai singled out what he referred to as "unilateral" NATO airstrikes and said that "if the lives of Afghans are not safe then strategic cooperation between the two countries will lose its meaning and concept."

Last week, U.S. President Barack Obama flew to Afghanistan to sign a memorandum of understanding alongside Karzai. It outlines promises and expectations between the two countries after the planned final withdrawal of American troops in 2014.

New Taliban offensive

On Monday, the Afghan government also condemned a recent announcement by the Taliban regarding the start of their annual "spring offensive," which begins every year as snows melt and the weather warms across Afghanistan. The offensive normally leads to a surge of militant attacks throughout the country as the Taliban attempt to retake lost territory and intimidate the government.

The Taliban announcement last week was another sign of the difficulty of reconciling with a group that has been fighting the U.S.-led coalition and Afghan forces for more than a decade. The Taliban said they would target anyone — from government workers to tribal leaders — who works against them and helps foreigners in their "occupation" of Afghanistan.

On Monday, the Interior Ministry said that "while again declaring war against the Afghan people, their government and constitution, the Taliban insurgents also abuse their religious values in the name of a cause opposed to the basic Islamic principles of peace, education and kindness."

The ministry statement said the Taliban use propaganda and "twist holy religious values to justify their criminal activities," which have killed thousands of innocent people.

Last year was the deadliest on record for civilians in the Afghan war, with 3,021 killed, according to the United Nations. Taliban-affiliated militants were responsible for more than three-quarters of those deaths.

The uptick in violence comes as NATO gears up to hand over security to local forces ahead of a 2014 deadline for the withdrawal of foreign combat troops. Some have questioned if local forces will be up to the task.

On Monday, a bomb killed three NATO service members in the east, the coalition said. It did not provide details about the attack nor the nationality of those killed. NATO usually waits for member nations to provide details about troop deaths. So far this year, 142 coalition members have died in Afghanistan.

Prisoners secretly released

The Washington Post also reported Monday that the U.S. military has been secretly releasing high-level detainees from the Parwan detention centre near Kabul to help with the reconciliation process. Many high-level Taliban detainees are held at the facility, which is run by the U.S. military but will be handed over to the Afghans within six months under a recently signed agreement.

U.S. Ambassador Ryan Crocker told the newspaper that many times the United States had acted on information that "might strengthen the reconciliation process."

"Ambassador Crocker was referencing a two-year old, rarely used program in which senior military officials, together with their Afghan counterparts, weigh the benefits of releasing certain individuals who are being detained at the Parwan Detention Facility and who are willing to denounce violence and engage in the process of reconciliation," U.S. Embassy spokesman Gavin Sundwall told The Associated Press.

Sundwall said fewer than 20 detainees have ever been released under the program and that the decision takes into account whether they pose any further security threat.

In the latest violence, four gunmen took over a tall building in the eastern province of Paktika late Sunday and started shooting down into surrounding government compounds, wounding one civilian. A spokesman for the governor, Mokhlis Afghan, said police surrounded the building in the provincial capital and killed the attackers after several hours. NATO and Afghan soldiers provided support.

Also Monday, the governor of southern Helmand province condemned a NATO airstrike last week that he said killed six civilians — a woman, three girls and two boys. Gulab Mangal said Friday's strike was aimed at insurgents attacking NATO and Afghan forces in the province's Sangin district. He said "a civilian house was also targeted by the airstrike unintentionally."

Mangal said U.S.-led NATO forces confirmed the recent event and apologized, saying it would help the remaining members of the family.