(Recasts to show probe has been expanded, adds background)
By Tim Hepher and Cyril Altmeyer
PARIS, March 16 (Reuters) - Airbus's legal entanglements deepened on Thursday when French authorities opened a preliminary investigation into suspected irregularities over the use of third-party agents to win jetliner contracts, expanding a UK corruption probe.
The European planemaker said on Thursday it had been informed that France's financial prosecutor, or Parquet National Financier, had teamed up with Britain's Serious Fraud Office, which is investigating suspected fraud, bribery and corruption.
"Airbus has now been informed ... that the two authorities will act in coordination going forward," the aerospace group said. "Airbus will cooperate fully with both authorities."
The decision by the French and UK investigators to cooperate in their probes is unusual.
It could provide a high-profile test of a 2016 anti-graft law which introduces for the first time into France the possibility of a "deferred prosecution agreement," a type of settlement often favoured in corruption probes and already used on occasion by Britain's SFO.
In January, UK engineering group Rolls-Royce Plc reached such a deal with the SFO and agreed to pay 497 million pounds plus interest plus SFO costs after a bribery probe.
The SFO launched its Airbus investigation last August after the planemaker uncovered evidence of false declarations over the use of agents in its applications for UK export credits and reported its findings to UK Export Finance, a government agency.
The UK agency last year suspended the issue of export credits to Airbus and France, and Germany followed suit, forcing Airbus to provide financing to some airlines in order to maintain aircraft deliveries.
Earlier this month, the company's sales chief told Reuters that some export credits could resume on a case-by-case basis this year.
Airbus, Europe's largest aerospace company, is headquartered in France.
The company is shaking up its international marketing organisation amid the UK probe, people familiar with the matter said last month.
The French and British investigations are separate from one initiated by Austrian prosecutors against Airbus and the Eurofighter consortium over alleged fraud.
Airbus also faces a French probe over a helicopter deal with Kazakhstan and a longstanding UK probe over bribery allegations in a communications deal between its GPT unit and Saudi Arabia.
(Additional reportnig by Kirsti Knolle and Mathieu Rosemain; Editing by Susan Thomas and Leslie Adler)