A bomb concealed on a bicycle has exploded in a crowded village market in the southern Afghan province of Helmand, killing at least 17 people and injuring 45 others including eight children.
Wednesday's attack occurred in Babaji, near the town of Lashkar Gah, the provincial capital of Helmand, where farmers had gathered to receive free seeds from government officials.
Local police said that the bomb had been strapped to a bicycle left in the market and detonated remotely.
An earlier report quoting a provincial government spokesman said a suicide bomber had blown himself up.
The casualties were all farmers who had gathered in the area to receive free seeds from the government as part of a program to encourage them not to plant opium poppy, Daoud Ahmadi, a spokesman for the provincial government, said.
Lashkar Gah is near Marjah in Helmand province, the focus of a major Nato-led offensive against the Taliban.
Thousands of Nato and Afghan troops have launched a massive offensive in southern Afghanistan - the largest the country has seen since the 2001 US-led invasion.
A major offensive in Kandahar, once a Taliban stronghold, would follow the current military operation in neighbouring Helmand province,which appears to have largely pushed back the Taliban and given the government a chance to take control.
Marjah is also thought to be the hub of the Taliban-controlled opium trade - which provides them with most of their funding.
The Afghan defence ministry has said the anti-Taliban push will be led by Afghan security forces as part of plans to hand over military and police responsibility to the Western-backed government.
The US and Nato have about 113,000 troops fighting in Afghanistan, with another 40,000 being deployed in the coming months.