Iran has drawn international attention to the targeted assassinations and abductions of its personnel abroad — its appeal following the killing of one of its border guards who had been kidnapped as part of a five-member group by a Pakistan-based militant group.

In a letter to Ban Ki-moon, the U.N. Secretary General, Iranian Foreign Minister, Mohammad Javad Zarif, internationalised the abductions and the death of its border guard.

He pointed to “the shocking news about the possible murder of one of the five Iranian border guards abducted on February 7, 2014 by an extremist terrorist group, in the border area between Iran and Pakistan.”

The death of the Iranian soldier, confirmed on Monday by Ali Asghar Mirshekar — the governor general of Iran Sistan-Balochistan province — seems to have added another irritant to the complex relationship between Tehran and Islamabad.

On Sunday, the Pakistan-based militant group, Jaish-ul-Adl had tweeted that Jamshid Danaeifar, one of the abductees, had been killed.

Iran’s Foreign Ministry asserted on Tuesday that Pakistan should be held accountable for the death of the Iranian border guard. Ministry spokesperson Marziyeh Afkham exhorted Islamabad to take “serious and prompt” action against the kidnappers, and guarantee the release of the Iranian soldiers.

She warned that lack of seriousness in Pakistan’s response could damage friendly and brotherly ties.

“Iranian officials have repeatedly expressed their dissatisfaction with and concern about acts of terror in border areas and the Islamic Republic of Iran has stressed the need for the necessary measure by Pakistan to prevent terrorists from crossing and using the Pakistani territory.”

In his letter, Mr. Zarif drew the Secretary General’s attention to the two car-bombings of the Iranian diplomatic and cultural premises in Beirut on November 19 last, which was followed three months later by another blast that killed one diplomat and a dozen security guards, along with several Lebanese civilian bystanders.

Without naming any particular country, Mr. Zarif stressed that all evidence indicated that “state-sponsored” extremist groups have been responsible for the terror attacks on Iran and its citizens.