Washington's special envoy on hostages, Adam Boehler, made a rare visit on Saturday to Kabul to discuss the possibility of a prisoner exchange, Taliban and US officials said.

"Adam Boehler, referring to the issue of detained citizens between Afghanistan and the United States, said that both countries will exchange prisoners," Afghanistan's deputy prime minister Abdul Ghani Baradar's office said after their meeting.

US Secretary of State Marco Rubio stopped short of confirming an exchange would take place, saying Boehler had gone to Kabul to "explore what's possible".

"Our special envoy for people unlawfully detained has been having conversations for a while," Rubio told reporters as he headed to the Middle East.

"Obviously, it'll be the president's decision in terms of any trades or any exchanges, but we most certainly want any Americans or anyone who's being unlawfully detained to be released. And so he went there to explore what that would look like."

At least one US citizen, Mahmood Habibi, is held in Afghanistan.

The United States is offering a US$5 million reward for information to find him, with the Taliban authorities denying any involvement in his 2022 disappearance.

Another American, airline mechanic George Glezmann, was freed after more than two years in detention during a March visit to Kabul by Boehler.

The US official -- accompanied Saturday by Washington's former envoy to Kabul, Zalmay Khalilzad -- also discussed detainees during a meeting with Afghanistan's Foreign Minister Amir Khan Muttaqi.

"Both sides emphasised that they will continue to discuss various existing and future issues in bilateral relations, especially those citizens who are imprisoned in both countries," government spokesman Hamdullah Fitrat wrote on X.

Dozens of foreign nationals have been arrested since the Taliban returned to power in August 2021 following the withdrawal of the US military. (AFP)