NEW DELHI (Reuters) - Airbus AIR.PA Chief Executive Tom Enders said on Friday he was not surprised by a French decision to investigate Airbus plane sales and said the firm had shown the effectiveness of its compliance rules by uncovering irregularities.

Airbus Group Chief Executive Tom Enders speaks during a news conference on the aerospace group's annual results, in London, Britain February 24, 2016. REUTERS/Hannah McKay

The French authorities on Thursday opened a preliminary investigation into suspected irregularities over the use of third-party agents to win contracts, expanding a UK corruption probe.

“This is the result of us self-reporting on observations made on irregularities with respect to business partners,” Enders said at a new pilot training center in India, adding that the discovery of the irregularities was not a new development.

“Not surprisingly they have decided to launch an investigation,” he said of the French decision.

He said uncovering the irregularities showed “very intensive company investigations” in line with Airbus’s compliance codes.

Britain’s Serious Fraud Office launched an investigation in August after the planemaker uncovered evidence of false declarations over the use of agents in applying for UK export credits and reported its findings to the British authorities.

Shares in Europe’s largest aerospace company fell around one percent, in a slightly stronger French market.

The decision by French and British investigators to cooperate is unusual. It could test a 2016 anti-graft law which introduces in France the possibility of a “deferred prosecution agreement,” a type of settlement often favored in corruption probes and already used by Britain’s SFO.

Britain last year suspended the issue of export credits to Airbus, and France and Germany immediately followed suit, forcing Airbus to provide financing itself to some airlines in order to maintain aircraft deliveries.

The system remains suspended but Airbus has suggested export support may return on a case-by-case basis later this year.