Switzerland says it has frozen nearly $1bn worth of assets linked to Libya's Muammar Gaddafi and the deposed leaders of Egypt and Tunisia.

Swiss Foreign Minister Micheline Calmy-Rey said some 830m Swiss francs ($960m) had been discovered.

Of that, the largest proportion - 410m SFr - was linked to former Egyptian President Hosni Mubarak and his circle, the minister said.

Another 360m SFr was believed to belong to Col Gaddafi's regime.

A further 60m SFr was tied to former Tunisian leader Zine al-Abidine Ben Ali and his associates.

Calmy-Rey revealed the amounts at a conference in Tunisia, where she is on a three-day visit, foreign ministry spokesman Lars Knuchel said.

"These amounts are frozen in Switzerland following blocking orders by the Swiss government related to potentially illegal assets in Switzerland," she said.

"It is not just money, there are real estate assets," she added.

Switzerland initially ordered the Ben Ali and Mubarak assets frozen after they were toppled in popular uprisings in January and February.

The assets of Col Gaddafi and his associates were blocked in February after he cracked down on opposition protests.

However, it is only now that the Swiss authorities have revealed details of the assets they have located and secured, BBC reports.

The new governments in Tunisia and Egypt have contacted Switzerland seeking to reclaim the funds, he said.

But neither country had yet given enough evidence that the money had been obtained illegally for Switzerland to release it.

There had been no such discussions with Libya, where Col Gaddafi remains in control of much of the country despite a popular rebellion.