The South Korean government has declined to comment on claims by Afghanistan's Taliban that it had freed two South Korean hostages.
On Saturday, Taliban insurgents who have held 21 Koreans captive for nearly a month said they had released two female hostages without any conditions, however Afghanistan government officials said they had no knowledge of such a release.
A South Korean government official, who asked not to be identified, told Reuters by telephone on Sunday: "We have no comment on the reports. But we are maintaining a direct contact with (the) Taliban."
The government will confirm reports and make comments when it secures hostages, he added.
Families of the hostages did not make a comment either.
"We are waiting for an official confirmation from the government," Cha Sung-min told Reuters at Saemmul Church, which sent the group to Afghanistan.
The group of Korean church volunteers, including Cha's sister, were seized on July 20 in Ghazni province and thought to be held there.
The Taliban have killed two male hostages who were part of a group of 23 people sent by the church in suburban Seoul on a humanitarian aid mission. Of the remaining hostages, 18 are women.
Talks between the insurgents and South Korean diplomats on the hostages started on Friday.
On Saturday, the Taliban said the talks were going well and the hostages would be freed in a prisoner swap, although a provincial governor was less optimistic.
The South Korean government is under intense domestic pressure to secure the safe release of the hostages, but has no power on its own to grant the kidnappers' demand for a swap with Taliban prisoners held by the Afghan government.
Afghanistan's authorities and allies like the United States fear releasing Taliban prisoners in exchange for the Koreans would encourage more kidnappings.
Afghan officials have previously ruled out any prisoner swap and have threatened to free the hostages by force if necessary.
The talks were held at a Red Crescent building in the city of Ghazni where the Afghan government has guaranteed the safety of the Taliban negotiators.
The Taliban say they have split the hostages into small groups and said any use of force to try to free them would put their lives at risk.