Two Pakistani diplomats based in a consulate office in the eastern Afghan city of Jalalabad have been missing since June 16, when they set off by road back to their homeland, according to Pakistan's foreign office.
The officials disappeared while travelling between the Torkham border crossing and Jalalabad, capital of Nangarhar province.
"The matter has been raised with the relevant Afghan authorities for their safety and recovery, at the earliest," Pakistan's foreign ministry said in a statement on Sunday.
In response, Afghan authorities have sent three investigation groups to ensure the officials' safe return, the statement said.
"Pakistan has requested the Afghan government that all efforts may be made to ensure early recovery of our officials and bring the perpetrators of this heinous crime to justice."
Attaullah Khugyani, a spokesman for Nangarhar's governor, told DPA news agency the "provincial governor has started efforts to search for and recover the Pakistani consulate workers with the full cooperation of the Pakistani consulate here."
Pakistan did not speculate who may be behind the disappearances but various Afghanistan-based groups have attacked diplomats in the past.
Afghanistan has accused Pakistan of turning a blind eye to Afghan Taliban commanders based within its borders and of supporting the group, something Pakistan denies.
Pakistan has claimed that Afghanistan is not doing enough to tackle Pakistan Taliban fighters who have been driven out of Pakistan, but who still carry out attacks across the border.
Jalalabad is a busy trading hub about 70km from the main border crossing with Pakistan, from which landlocked Afghanistan imports much of its goods.
The province is home to various armed groups, including the Pakistani and Afghan Taliban.
Source: News agencies