The minister broke the news today, saying he was notified unofficially by the Cambodian authorities about the good news which is expected to be announced officially later today.
Mr Surapong said Ratree Pipattanapongpiboon, a member of the Thai Patriots Network now serving a jail term in Cambodia for spying and illegal entry, will be released on February 1 during the royal cremation of Cambodia's late king Norodom Sihanouk, father of King Norodom Sihamoni.
In addition, Veera Somkwamkid, her companion in the misadventure and fellow member of the network, will be given a six-month clemency.
The foreign minister said both activists' families will be informed about the news. It is considered a goodwill gesture for bilateral relations, the minister said.
Prime Minister Yingluck said the Cambodian government informed her about its decision and she thanked the neighbouring country's government for its cooperation.
Ms Yingluck added that she often brought up the issue at bilateral discussions and during her visit to the neighbouring country and follow up the case periodically.
The government is duty-bound to help all Thais, no matter who they are, she said.