An explosion on Wednesday hit a bus travelling on a highway between two key cities in western Afghanistan, killing at least 34 passengers, including children, and injuring 17, officials said.
Security has been deteriorating across Afghanistan, with the Taliban and Islamic State fighters mounting near-daily attacks on Afghan forces, government employees and civilians.
The blast on the highway linking the provincial capitals of Herat and Kandahar took place in the Ab Khorma area of Farah province, said provincial police spokesman Mohibullah Mohib.
"The bomb was freshly planted by the Taliban insurgents to target Afghan and foreign security forces," he said.
Taliban officials were not immediately available to comment on the statement and there was no immediate claim of responsibility for the attack.
Government and aid officials say the numbers of those being killed and maimed is rising because of explosives newly planted by the Taliban, who now control more territory than at any point since their ouster nearly 18 years ago.
Wednesday`s blast comes ahead of presidential elections next month, when US officials and Taliban representatives are also due to resume talks to agree a timetable for the withdrawal of foreign forces in exchange for security guarantees.
Security has been deteriorating across Afghanistan, with the Taliban and Islamic State fighters mounting near-daily attacks on Afghan forces, government employees and civilians