Image caption Nearly all French regional education authorities got involved in the competition

France's external intelligence service, the DGSE, has sponsored a school competition to find the nation's most talented young code-breakers.

It has 6,200 staff - 63% of them civilians - and an annual budget of about €750m £575m; $839m .

The DGSE's role was to provide some help and funding for it, its spokesman told the BBC.

The official declined to be named.

The organisers said boys and girls competed in almost equal numbers.

In recent years British spy agency GCHQ has also set cryptographic challenges for the general public on the internet.