BRUSSELS (AP) -- Airbus has achieved a milestone in its long-delayed A400M military airlifter program, testing all four of the plane's turboprop engines together amid pressure from customer countries to get the plane airborne.

Europe's Airbus said Thursday that the new Europrop International TP400 engines performed flawlessly during four hours of ground testing Wednesday at low power settings. They will be run up to full power in coming days, the company said.

The prototype's first flight is expected to take place before the end of December.

The four-engine A400M was launched in 2003 with an order for 180 planes from seven governments, and is Europe's most ambitious collaborative military transport program ever. But the program has been hit by cost overruns and problems with the TP400 engines, and the plane's maiden flight has been repeatedly postponed.

Problems with the prototype's weight also contributed to pushing first deliveries -- originally scheduled for 2009 -- to 2012. The delays caused Airbus to lose a number of potential sales to air forces in South Africa, Norway and Canada.

Also on Thursday, Germany hosted talks in Berlin of state secretaries from all the countries that ordered the plane, but released no details of their meeting. Earlier this year defense ministers from the seven nations -- Belgium, Britain, France, Germany, Luxembourg, Spain and Turkey -- agreed to re-negotiate the contract.

Participating nations have warned Airbus that any further delays would not be tolerated, and that if the prototype does not take to the sky by the end of February some of the participants could pull out of the joint venture.

Within Airbus, Airbus Military is responsible for the A400M program, for light and medium-sized military transport aircraft, and tanker derivatives based on Airbus civil aircraft.

Associated Press writers Dave Rising in Berlin and Emma Vandore in Paris contributed to this report.