Hundreds of people were stranded Saturday at a key border crossing between Pakistan and Afghanistan, days after fighting between security forces left at least three dead. Border tensions have risen since the Taliban’s return to power last year, with Pakistan alleging militant groups are planning attacks from Afghan soil. The Taliban deny harbouring Pakistani militants, but are also infuriated by a fence Islamabad is erecting along their 2,700-kilometre (1,600-mile) border, drawn up in colonial times and known as the Durand Line. Each side blamed the other for Thursday’s fighting at the Chaman-…