JALALABAD, Afghanistan - A Taliban suicide car bomb targeted a NATO convoy in eastern Afghanistan Friday, killing at least three civilians as security forces brace for a full-blown insurgent offensive in the spring fighting season.
Separately, 12 civilians onboard a minivan were killed when a roadside bomb struck their vehicle in the militant-infested southeastern province of Ghazni.
The civilian fatalities come as Taliban insurgents step up attacks on government and foreign targets after Washington announced a delay in US troop withdrawals from Afghanistan last month.
"In the morning today a foreign forces convoy came under a suicide attack near the airport in Jalalabad city," provincial police spokesman Hazrat Hussain Mashriqiwal told AFP.
He added that three civilians were killed and four others were wounded in the powerful explosion in Jalalabad, which is home to an important US military base.
Resolute Support, the new name for the NATO mission in Afghanistan, did not officially comment on the incident but in a brief Twitter posting denounced it as "yet another senseless attack by the Taliban".
Roadside bombs - like the one in Ghazni - have been a weapon of choice for the Taliban in their 13-year war against foreign and Afghan forces, though the militants seldom admit blame for attacks resulting in civilian casualties.
The Taliban, however, claimed responsibility for the NATO convoy attack in Jalalabad as Afghan forces brace for what is expected to be a bloody spring-summer push by the insurgents.
Friday's bombings come a day after 18 people were killed when Taliban insurgents mounted a six-hour gun and grenade siege on a courthouse in the usually tranquil northern city of Mazar-i-Sharif.
The militants said they were behind the terrifying assault, which underscored Afghanistan's precarious security situation as US-led foreign troops pull back from the frontlines after a 13-year war against the Taliban.
In a statement on Friday, President Ashraf Ghani "strongly condemned the group terrorist attack in which a number women and children were martyred and many others were wounded".
The uptick in attacks in recent days has taken a heavy toll on ordinary Afghans.
The number of civilians killed and wounded in Afghanistan jumped 22 per cent in 2014, a recent UN report said, as NATO troops withdrew from combat.
The United Nations Assistance Mission in Afghanistan attributed the rise to an intensification in ground fighting, resulting in a total of 10,548 civilian casualties last year.
NATO's combat mission formally ended in December but a small follow-up foreign force has stayed on to train and support the local security forces.
President Barack Obama last month backpedalled on plans to shrink the US force in Afghanistan this year by nearly half, an overture to the country's new reform-minded leader, Ghani.
Hosting Ghani at the White House for their first presidential head-to-head, Obama agreed to keep the current level of 9,800 US troops until the end of 2015.
The Taliban, who have waged a deadly insurgency since they were ousted from power in late 2001, warned that the announcement would damage any prospects of peace talks as they vowed to continue fighting.
An American soldier was killed on Wednesday by an Afghan counterpart in eastern Afghanistan, the first insider attack since Obama's announcement.