BBC: News of a $400m Franco-Libyan arms deal has reignited a controversy in France about how the release by Tripoli of jailed medics was secured last week.
The six were freed after a high-profile visit to Libya by President Nicolas Sarkozy's wife, Cecilia.
The day after their release, the president himself flew to Libya to sign trade and health deals.
Since then, opposition socialists have demanded to know whether the Bulgarian detainees were part of the package.
Mr Sarkozy strongly denies that there was any such quid-pro-quo.
But the arms agreement - the first between Libya and a Western country since the EU lifted a ban in 2004 - has fuelled demands for explanations.
The deal was first outlined on Thursday by Saif Gaddafi, the son of the Libyan leader.
He told Le Monde newspaper that the arms sales had long been at the heart of talks between Libya and France. Libya sales deal fuels French row (more) By Henri Astier
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France-Libya arms deal probed
Mark Alexander
