Much of the violence, some of the fiercest since the Taliban's ousting, occurred in Helmand and Kandahar provinces on Thursday, where thousands of additional Nato troops are to deploy this summer to counter an increasing number of insurgent attacks.
US and Afghan officials said the Taliban toll from fighting on Wednesday night and Thursday ranged up to 87.
The attacks also killed 15 Afghan police officers, one American civilian, a Canadian soldier and an Afghan civilian.
An assault by hundreds of Taliban fighters on a small southern town was one of the largest attacks by militants since 2001 and marked an escalation in the campaign by supporters of the former Taliban government to challenge the US-backed government of Hamid Karzai, the president.
The attack late on Wednesday and early on Thursday on a police and government headquarters in Musa Qala in Helmand province sparked eight hours of clashes with security forces.
The interior ministry said about 40 militants were killed, though police said they had retrieved only 14 bodies. The ministry said 13 police were killed and five wounded in the attack.
Captain Drew Gibson, a spokesman for the British military, said the assault was countered by Afghan police reinforcements who forced the militants to flee.
The US-led coalition, meanwhile, said up to 27 Taliban were killed in fighting in neighbouring Kandahar province on Thursday.
The military said there were seven confirmed deaths and that 15 to 20 may have been killed in an associated air strike near the village of Azizi.
Afghan police secure a suicide
car bomb blast site in Kandahar
In another battle in Kandahar province, a Canadian soldier and about 18 Taliban fighters were killed late on Wednesday.
Major Scott Lundy, a Canadian military spokesman, said Canadian soldiers were supporting Afghan forces on a mission to oust Taliban fighters in Panjwayi district, about 30km west of Kandahar city, when they were engaged by rocket propelled grenades and small arms fire.
A female Canadian soldier, Captain Nichola Goddard, was killed, Lundy said.
Three Afghan soldiers were wounded, and about 35 militants were detained, he added.
A roadside bomb in Kandahar city exploded near an Afghan army convoy on Thursday, wounding two civilians, police officer Sher Shah said. No soldiers were wounded.
Chris Harris, the US embassy spokesman, said a suicide car bomber in the western city of Herat, near the Iranian border, killed an American civilian and wounded two others.
A second suicide car bomb attack occurred near the gates of an Afghan army base in the town of Ghazni, 120km south of Kabul.
Sher Alam, the provincial spokesman, said the attack killed the bomber and a civilian passing on a motorbike, and a man walking in the area was wounded, but none of the soldiers at the base was hurt.
In Ghazni, rebels ambushed two police patrols, killing two officers and wounding five, including the provincial deputy police chief.
The escalating violence in the south, with militants launching increasingly bold attacks and suicide bombings, comes as Nato prepares to take over control of security operations from the US-led coalition, which has been hunting for Taliban and al-Qaeda militants in the region since late 2001.
Troops from nations including Canada, Britain and the Netherlands will be stationed in the south.