Four soldiers of the Pakistan Army were martyred and one other was injured in two separate incidents of firing by militants near the Afghan border, the military's media wing said on Saturday.

The first incident occurred in North Waziristan tribal district, where miscreants opened fired on a routine patrolling party of security forces near Abba Khel area of Spinwam tehsil late on Friday night, according to a statement issued by the Inter-Services Public Relations (ISPR).

As a result, 23-year-old Sepoy Akhtar Hussain, a resident of District Baltistan, embraced martyrdom.

"In exchange of fire, two miscreants [were] killed," the ISPR said.

In a separate incident in Dir, suspected terrorists opened fire from across the Pak-Afghan border on Pakistan Army troops who were busy in border fencing.

"3 soldiers embraced shahadat while 1 got injured" in the incident, the military's media wing said.

The personnel martyred in the second incident include Lance Naik Said Amin Afridi, aged 28, a resident of District Khyber; Lance Naik Muhammad Shoaib Swati, a 31-year-old resident of District Manshera; and Sepoy Kashif Ali, aged 22, a resident of District Nowshera.

Later in the day, the Foreign Office (FO) summoned the Afghan Charge d’ Affairs to lodge a formal protest against the firing incident.

"A strong demarche was made over the latest incident of firing on a Pakistan military contingent engaged in completion of fencing of Pakistan-Afghanistan border," the FO said in a statement.

"The unprovoked firing resulted in martyrdom of three Pakistani soldiers while seriously injuring one of them," the FO statement read. It added, "While strongly condemning the attack, it was underscored that the Afghan side was responsible for securing the areas on its side of the border, as mutually agreed on several occasions."

According to the statement, Pakistan once again calls upon the Afghan government to do the needful to secure the border areas, especially along the sensitive points, to maintain the level of cooperation needed to effectively counter terrorist elements in their areas.

The attacks come less than two months after 10 Pakistani armed forces personnel were martyred by militants, six of them in a cross-border attack in North Waziristan district and four others in an assault in Kech district of Balochistan. The ambush in North Waziristan was claimed by the banned Tehreek-i-Taliban Pakistan.

The FO had last month asked Afghanistan to fulfil its commitment for the elimination of terrorist hideouts along the Pak-Afghan border.

“As a matter of policy, Pakistan does not fire across the Pak-Afghan border. Cross-border attacks by terrorists on army/FC posts are responded to in self-defence only,” a foreign ministry statement had said at the time.

Pakistani forces have conducted a series of operations against militant groups in the tribal districts of Khyber Pakhtunkhwa over the years. While officials say the area has largely been pacified, small attacks continue to take place.