KABUL, Afghanistan -- Insurgents killed six police officers at a checkpoint and a suicide bomber killed three civilians at a shopping bazaar in separate attacks Sunday in eastern Afghanistan, while an independent security group warned 2013 is on track to be one of the most violent years of the war.

April already has been the deadliest month this year for security forces and Afghan and foreign civilians as the U.S. and other countries prepare to end their combat mission by the end of next year. According to an Associated Press tally, 222 people have been killed in violence around the nation this month, including Sunday's nine fatalities.

The Taliban ambushed the checkpoint in the Dayak district of Ghazni province, killing six police officers, wounding one and leaving one missing, said Col. Mohammad Hussain, deputy provincial police chief. The checkpoint was manned by Afghan local police, forces recruited at the village level that are nominally under the control of the Afghan Interior Ministry.

On Friday, Taliban insurgents attacked a local police checkpoint in Andar, a district of Ghazni province neighbouring Dayak. They killed 13 officers, according to Sidiq Sidiqi, the Interior Ministry spokesman.

The second attack on Sunday hit Paktika province, which borders Ghazni. A suicide bomber detonated his explosives in a shopping bazaar around midday, killing three people and wounding five civilians and two police officers, said Mokhlis Afghan, the spokesman for the provincial governor. Among the dead was Asanullah Sadat, who stepped down as the district's governor two years ago.

Zabiullah Mujahid, a spokesman for Taliban, claimed responsibility for the suicide bombing. In an email to reporters, he said the Taliban used the bomber to target Sadat because of his close relations with the Afghan government and the U.S.

In other violence, the Taliban cut a hand and foot off each of two villagers they accused of helping escort coalition convoys, a spokesman for the provincial chief in western Herat province said.

Noor Khan Nekzad said the men were admitted to a hospital in Herat city on Sunday, two days after the amputations. The Taliban have long killed government employees and those who help the coalition, considering them enemy collaborators, but rarely have they meted out punishment by cutting off limbs.

Hostilities have surged in Afghanistan as the spring fighting season begins. This year is being closely watched because Afghan forces must operate with less support from the international military coalition. With foreign forces due to hand over combat responsibilities to the local forces next year, the current fighting is a test of their ability to take on the country's insurgency.

Reflecting the rise in bloodshed, the Afghanistan NGO Safety Office said Sunday there were 2,331 insurgent-initiated attacks in the first quarter of this year, a 47 per cent increase over the same January-March period last year. "We assess that the current re-escalation trend will be preserved throughout the entire season and that 2013 is set to become the second most violent year after 2011," which suffered 2,755 such attacks in the first three months of the year, the report said.

The U.S.-led NATO coalition has stopped releasing statistics on insurgent attacks in Afghanistan.

Afghanistan's Defence Ministry said the Afghan army carried out 2,209 military operations during a monthlong period ending Sunday. During that time, 467 insurgents and 107 soldiers were killed, and 362 militants were arrested, the ministry said in a report issued Sunday.

The rise of violence that his organization reported in early 2013 should raise serious concern, especially since a negotiated solution with Taliban "is far from the horizon" and questions remain about whether Afghan forces can fill the gap being left by the reduction in U.S.-led international forces, said Tomas Muzik, the director of the Afghanistan NGO Safety Office.

The Taliban broke off formal talks with the Americans last year and have steadfastly rejected negotiations with the Afghan government, which they view as a puppet of foreign powers.

Afghanistan has about 100,000 international troops, including 66,000 from the United States. The U.S. force is to drop to about 32,000 by February 2014, making the No. 1 priority for the American military to do all it can to boost the strength and confidence of Afghan forces.