The attacks came only one day after another suicide attack killed a senior Canadian diplomat and two Afghans, while wounding another three Canadian soldiers.
Glyn Berry, director of the Canadian reconstruction team in the region, was killed in a suicide attack Sunday in Kandahar. Officials said the attack took place when an explosives-laden vehicle swerved into the jeep in which Berry was riding.
Afghan officials said they viewed the increased attacks as an effort to destabilize the international effort to aid the fledgling Afghan state.
"They want to scare NATO and also tell donors Afghanistan has not gained stability and their aid will be wasted," Rangeen Dadfar Spanta, an adviser to Afghan President Hamid Karzai, told Reuters.
In an apparent effort to bolster the international effort, Karzai, speaking ahead of a foreign donors' conference in London later this month, warned the struggle in Afghanistan against Taliban and al-Qaida elements needed to be a multinational effort.
"We are in a joint struggle against terrorism, for us and for the international community," he told reporters. "If you don't defend yourself here, you will have to defend yourself back home, in European capitals and Americans' capitals."
"It will take many, many more years before we can defend ourselves with our own means, before we can feed ourselves or work for our development with our own means," Karzai added.
Monday's attacks in the restive southern region of the country targeted only Afghans. The first bombing on Monday struck an Afghan Army convoy in Kandahar, the same city where Berry was killed on Sunday.
There were conflicting reports as to whether the convoy attack was the work of a suicide bombing or a roadside explosive, but one soldier and three passers-by were killed, while six troops and 10 civilians were wounded.
"One of the trucks was totally destroyed. The soldiers were thrown from the back and it hit so many people standing on the street," Abdul Khan told Reuters.
Just hours later, a suicide attacker on a motor bike rode among a group of 100 Afghans attending a festival in the southern city of Spinboldak and detonated his explosives, killing at least 20 and wounding another 20.
Taliban official Mullah Sabir Momin said the attack had been aimed at the commander of the Afghan border force, who was incorrectly thought to be at the event. Momin did claim that seven Afghan soldiers were among the dead.
"We plan more attacks on Afghan army commanders because they support the U.S. presence in Afghanistan," he said.
Officials in Kabul said they believed the new wave of attacks in the south were aimed at both destabilizing the central government and at slowing down NATO plans to expand its peacekeeping mission into the area.
Speaking at his fortified palace in Kabul, Karzai said increased use of suicide attacks showed Taliban desperation.
"[The attacks] cause insecurity, worry among people ... disrupt life. They are a matter of concern for us ... we will use all means to prevent them," Karzai said.
He added that political developments like the landmark presidential elections in 2004 and parliamentary balloting in September 2005 were also fueling the increased violence.
"We have succeeded, massively, and that political success is perhaps one of the reasons why we are so much under attack now," he said. "Therefore the success of Afghanistan should not mean a reduction of attention, but more attention."
Also Monday, U.S. military spokesman Col. James Yonts said U.S.-led coalition forces had noticed an apparent shift in Taliban targets, moving away from direct assaults on military forces and towards guerrilla-style attacks against less-protected targets.
"The enemy knows he cannot defeat us militarily," Yonts told reporters. "He is shifting his tactics to soft targets. He will strike without warning and he will strike, as we have seen, unfortunately against civilians."