According to the Inter-Services Public Relations, the media wing of the army, the terrorists attacked the security post in Dera Ismail Khan's Daraban area bordering the South Waziristan tribal district in the early morning hours.
The special court of Islamabad on December 17 last handed down the death penalty to 74-year-old Musharraf after six years of hearing the high-profile treason case against him. The case was filed by the Pakistan Muslim League-Nawaz government in 2013.
Pakistan dismissed reports that Lashkar-e-Tayiba operative David Headley had linked serving Pakistani army officers to the 2008 Mumbai attacks, saying they were based on "misguided leaks" aimed at maligning the country.
A senior BSF officer said the three Pakistani soldiers strayed into this side of the border on Sunday evening, and were immediately arrested by the alert jawans of the BSF patrolling in the area.
The ex-army chief left for Dubai for medical treatment in March 2016 and has not returned since, citing security and health reasons.