More than a dozen militants have been confirmed dead as government forces increased pressure on the armed opposition groups in Afghanistan, officials said Monday.

The Afghan military has suffered its worst loss of the year in southern Afghanistan, with at least 40 security force members killed in a Taliban attack this past week, but senior officials had still not released a death toll two days later, according to residents and functionaries from the area who spoke on Sunday.

Afghan border security troops were asleep inside their remote post in southern Afghanistan early Friday when a Taliban infiltrator climbed a guard tower. Moments earlier, a lone sentry had left the post to wake his replacement.