Lockerbie bomber Abdelbaset Ali Mohmed Al Megrahi is to learn whether he will be released to return to Libya.
Scottish justice secretary Kenny MacAskill is expected to announce Megrahi's release on compassionate grounds.
The decision to free the convicted bomber is likely to cause outrage in the US where Secretary of State Hillary Clinton said she hoped he would stay behind bars.
Megrahi could be on his way home within days - possibly before the start of Ramadan at the weekend - to spend his dying days with his family.
Mr MacAskill will make the announcement at 1pm at the Scottish Government's ministerial headquarters in Edinburgh.
He has been considering two applications - one for Megrahi to be moved from Greenock prison to Libya under a prisoner transfer agreement, and a separate application for him to be released early on compassionate grounds. The latter course would see him return home a free man.
Announcing Mr MacAskill's plans to make a statement in Edinburgh, the Scottish Government said he had reached decisions on both - but did not say what they were.
A Scottish Government spokesman said: "We have a strong justice system in Scotland and people can be assured that the Justice Secretary's decisions have been reached on the basis of clear evidence and on no other factors."
The early notice of his announcement was said to be in line with a pledge by Mr MacAskill to inform families on both sides of the Atlantic of the timing of the announcement.
In the build-up to his decision, Mr MacAskill came under intense US pressure to keep Megrahi behind bars.
