"Reported cases must be investigated promptly and in a transparent manner, those responsible must be held accountable, and these steps must be clearly publicized as an immediate deterrent to further killings and disappearances," it said.
Afghan Interior Ministry spokesman Sayed Khosti rejected the accusation of reprisal killings, saying no evidence had been presented.
"If there is any evidence, it should be shared with us," he said in a video statement, pointing to the general amnesty announced by the Taliban government.
"We have had some individual cases of killings of ex-government members but these were due to private enmity and we've arrested those involved."
"This is slander against the Islamic Emirate of Afghanistan, not justice."
Human Rights Watch said in a report on Nov. 30 that Taliban forces in Afghanistan have executed or forcibly disappeared more than 100 former police and intelligence officers since taking over the country on Aug. 15, despite the proclaimed amnesty.
The Taliban interior ministry has rejected the Human Rights Watch report but said it would arrest anyone who could be shown to have carried out violent reprisals against members of the former military.
Facing a deep economic crisis following the abrupt withdrawal of foreign aid when Western countries pulled out of Afghanistan, the Taliban have been appealing for international support to stave off a humanitarian disaster, with more than half the population facing hunger over the winter.
The joint statement said, "We will continue to measure the Taliban by their actions".
The statement was issued by Australia, Belgium, Bulgaria, Canada, Denmark, the European Union, Finland, France, Germany, Japan, the Netherlands, New Zealand, North Macedonia, Poland, Portugal, Romania, Spain, Sweden, Switzerland, the United Kingdom, Ukraine and the United States.
(Reporting by Emma Thomasson and James Mackenzie Editing by Frances Kerry) ((+4930220133580;))