The incident occurred in Kunar province, governor Asadullah Wafa told Reuters. "Two coalition soldiers were killed and three others wounded," he said.
The Pakistan-based Afghan Islamic Press quoted a government district chief, Shah Mahmood Shaheed, as saying the two soldiers killed were American and their vehicle had hit a landmine.
It said Taliban spokesman Mohammad Hanif had claimed responsibility for the attack. Hanif said four Americans had been killed, the agency said.
A spokesman for the US military said he could not immediately comment on the reports.
Earlier, a US military statement said one US service member was killed and four injured on Wednesday when their armoured vehicle overturned in an accident in the southern province of Kandahar. It said the accident had not been caused by hostile activity.
More than 50 US soldiers have been killed in combat in Afghanistan this year, the bloodiest period for US forces since they overthrew the Taliban in 2001 for refusing to hand over al-Qaida chief Osama bin Laden, architect of the September 11 attacks.
Wednesday's violence comes after Washington announced this month that it planned to cut US troop numbers in Afghanistan to about 16,500 from 19,000 by next spring, despite a stubborn Taliban insurgency.
The Pentagon said the cut was made possible by a planned increase in Nato forces next year and the growing size of Afghan security forces.