KABUL A roadside mine killed 19 civilians and injured another five when it exploded in the southern Afghan province of Helmand on Wednesday, the provincial government said.
The blast came a day after rare sectarian attacks in three Afghan cities killed 59 people, and refocused attention on the fragile Afghan security situation.
After Tuesday's attacks, the largest of which targeted a Shi'ite Muslim shrine in the capital Kabul, Afghan President Hamid Karzai cancelled a planned visit to Britain to return straight home, wiping out any residual optimism from an international conference about the future of Afghanistan, held on Monday in Germany.
Afghans have previously been spared the large-scale sectarian attacks that regularly trouble Iraq and neighboring Pakistan, but now face the grim prospect of a new type of bloodshed being added to the dangers of daily life.
"The reason for President Karzai's trip cancellation to Britain is the terrorist attacks on Ashura in Kabul, Mazar-i-Sharif and Kandahar which killed and wounded many participants," Karzai's office said in a statement.
The NATO-led International Security Assistance Force (ISAF), responsible for security across much of the country, says it is winning the war against the Taliban.
But if Tuesday's bombing sets a precedent for violence between the Sunni Muslim majority and the Shi'ite minority, it would severely stretch army and police resources.
At a funeral ceremony on Wednesday for victims of the attack, hundreds of Shi'ite Muslims bore aloft the bodies of the dead, chanting that because they had been killed at a Muslim ceremony, they had died in the name of the Prophet Mohammad.
"We were sacrificed for you," they shouted.
"Where is the government, where are the members of parliament? Why they don't join our mourning? It creates a gap between people and the government," said Mohammad, 40 years old, who said one his relatives died in the Kabul blast.
The interior ministry has blamed "the Taliban and terrorists", without giving further details, while the Taliban strongly condemned the bombings.
"We want the Afghan government, international community and those who are involved in Afghanistan's affairs to reveal those who were behind the attack," said Yazdan Parast, another Shi'ite Muslim attending the ceremony.
Some Shi'ite Muslims said immediately after the Kabul blast that police had not done enough to protect them. Hundreds of worshippers had gathered to mark the festival of Ashura at a shrine in central Kabul when a suicide bomber struck.
Among those killed in Tuesday's attacks was a U.S. citizen the American embassy in Kabul said in a statement. It gave no further details.
At the German conference, the Afghan government's Western backers, who have spent billions of dollars on the country since the U.S.-led overthrow of the Taliban government in 2001, pledged to support the country beyond the end-2014 deadline for the withdrawal of foreign combat troops.
Afghanistan has said that it will not be able to afford the army and police force it needs after 2014 without international help, and Tuesday's attack is likely to reinforce fears about the ability of Afghan forces to cope with violence after ISAF has fully handed over security.