French President Nicolas Sarkozy's plan to institute a minimum tax on large, listed companies based in France if he is re-elected will apply to groups with a market value of 1 billion euros (841.71 million pounds) and above, according to Finance Minister Francois Baroin.

The tax, which the government expects will raise an additional 2-3 billion euros annually to help cut the country's public deficit, would be based on companies' overall sales, Baroin said in an interview with RTL radio on Friday.

It's companies which have their headquarters in France and whose market capitalisation is at least a billion, the finance minister said. The rate hasn't been fixed yet.

We could take into account revenue more than the result. Global revenue, he added.

Sarkozy revealed his tax plan during a three-hour televised debate on Tuesday as the battle heats up between him and front runner Francois Hollande weeks away from the first stage of the two-round presidential election.

The president, who has been criticised on the left for changes to the tax system that favour companies and the wealthy, said in the debate on France 2 television that the tax would target international companies such as oil major Total.

Explaining the motive for the tax, to be proposed in the 2013 budget, Sarkozy said: I have discovered something which is not normal, it's that these big companies maximise their tax benefits and some of them do not pay tax at all.

Hollande dismissed the proposal as a belated act of contrition after five years in power.

(Reporting by James Regan. Editing by Jeremy Gaunt)