KABUL, Afghanistan -- Suicide attacks involving as many as 14 bombers struck an Afghan city Tuesday, and a motorcycle bomb exploded in a busy market in blasts that killed at least 46 people altogether -- the year's deadliest day for civilians in Afghanistan.

Most of those who died were out shopping for food to break the daily fast of the Muslim holy month of Ramadan.

The attacks in Nimroz province in the southwest and Kunduz in the north came during a campaign by Taliban insurgents and their allies to step up attacks as international troops hand over security responsibility to Afghan forces. NATO plans to withdraw most of its troops by the end of 2014.

There were no claims of responsibility for any of the blasts.

At least 25 civilians and 11 police were killed in Nimroz when several men wearing suicide bomb vests detonated their explosives in different areas of the provincial capital of Zaranj, provincial police chief Musa Rasouli said.

Not all of the attackers were able to set off their bombs. Police killed or captured several of them, officials said.

One explosion mid-afternoon Tuesday went off outside a hospital near a busy market packed with people shopping for the feast at the end of the Islamic holy month of Ramadan, which starts this weekend, officials said.

Nimroz Gov. Abdul Karim Barawi said there were three blasts in the city, but accounts by officials differed amid the chaos in the remote area that has had relatively few insurgent attacks in the past year.

At least two attackers wearing suicide bomb vests and carrying weapons also attacked the governor's compound but were killed by security forces before they could set off their explosives, Rasouli said.

Nimroz deputy police chief Abdul Majid Latifa said 14 bombers in all were involved in the plot, while Rasouli put the number at 11. Both said that two of the plotters were killed by police on Monday night and three more were either killed or arrested Tuesday morning, but their initial accounts of what happened on Tuesday afternoon differed.

Nimroz, in the southwestern corner of Afghanistan, is not as regularly beset by insurgent attacks as are Helmand and Kandahar to the east. The sparsely populated province is partly desert, and its government representatives have repeatedly complained that it is neglected by officials who are focused on its more volatile neighbors.

Recently, however, Nimroz has seen an increase in violence. On Saturday, an Afghan police officer killed 11 of his fellow officers in the remote Dilaram district of the province.

In Kunduz province in the north, police said a motorcycle bomb outside a crowded bazaar killed at least 10 people, including several children.

District police chief Hamid Agha said the bomb exploded in the early evening as shoppers were rushing home for the meal ending their Ramadan fast. He said five children were among the dead, and at least 25 people were wounded.

The combined death toll marks the deadliest day for Afghan civilians this year.

On June 6, a car bomb and a motorcycle bomb killed 22 people near Kandahar airport in the volatile south.

Another suicide attack July 14 on a wedding killed 23 people, including the provincial intelligence chief and two army generals.