The chief prosecutor at the UN's new court for Sierra Leone has repeated claims that the Libyan leader is behind the past decade of war in West Africa.
Gaddafi: In charge for more than three decades
The accusation against Muammar Gaddafi was made by David Crane in an interview with the BBC.
It comes at a time when Libya is trying to improve relations with the West.
The Sierra Leone war crimes court officially opens its doors this week, in the wake of international courts for the former Yugoslavia and Rwanda.
It has been known for some time that several West African rebel leaders were trained in Libya, but the accusations from war crimes prosecutor David Crane come at a politically sensitive time.
The Libyan leader has improved his relations with the United States and Britain, and sanctions have been lifted.
However, the US and Britain also support the new Sierra Leone war crimes court where - when cases start in the coming weeks and months - potentially explosive allegations will be made against the Libyan leader.
Mr Crane said there was a detailed plan by Mr Gaddafi to destabilise several West African countries which had caused widespread suffering in the region.
"We know that, specifically up until last year, that there was a 10-year plan to take down Liberia, Sierra Leone, Cote d'Ivoire, then move to Guinea and then elsewhere as the situation developed," he said.
"The 10-year plan was to put in surrogates who were beholden to Muammar Gaddafi," Mr Crane said.
The new Sierra Leonean war crimes court has indicted those deemed to have, in the legal phrase, the greatest responsibility for crimes against humanity in Sierra Leone.
When asked whether Muammar Gaddafi might be indicted, the chief prosecutor said he could not confirm this, but that all options were still open.