Silvio Berlusconi and Nicolas Sarkozy haven't agreed on very much about immigration of late, but yesterday they found common cause on at least one point: the Schengen agreement needs to change.

Since it was first put in place in 1995, 25 European states – with the notable exception of Britain – signed a deal creating free circulation within Europe for its citizens, but also for whoever had a travel permit to one of those countries. The accord was heralded as a great step forward, a cornerstone of an integrated Europe.

That consensus no longer stands. For while France and Italy agree that the deal is no good, they have very different ideas on how its terms should be implemented.

Since Tunisia's Jasmine revolution in December, Italy has seen 25,000 Tunisians arriving on its shore, all looking for a job. Unable to stem the tide, the Berlusconi administration has found a simple way of defusing the issue. Italy issued thousands of travel permits, thus allowing immigrants to travel freely within Europe. Many Tunisians being francophone, their first destination is often France.

The Sarkozy government objects to the way Mr Berlusconi is trying to "resolve" the problem by passing the bucket to another member state. However, on arriving in France, Tunisians have suddenly realised that their Italian travel permit doesn't amount to much because French police require them to hold a passport and have proof of an income.

With the next presidential elections looming in France, and an increasingly vocal National Front, Mr Sarkozy has to be seen to be acting tough on what many consider in France to be plain economic immigration (as opposed to political asylum, which at the moment befits Libyans rather than Tunisians). Mr Berlusconi is also the hostage of his coalition partner, the ever-stronger Lega Nord, another extreme right political party for whom immigration is a key electoral issue.

Whatever happens next, the imperative for both leaders yesterday was to avoid appearing to give ground to the other. They have both advocated special clauses "in exceptional circumstances" and a temporary return to border controls to monitor the ebb and flow of migrants from North Africa. With the events taking place in that part of the world, these "exceptional circumstances", even if agreed between the 25 states, might become more than temporary.

Agnès Poirier is a journalist and author of 'Touché: A Frenchwoman's Take On The English'