The head of European aerospace group EADS said on Tuesday that contracts with clients for the A400M military transporter may not be finalised for several months.

"If it can be done for the summer, that would be best, otherwise it will be in the autumn," Louis Gallois told AFP following a shareholders' assembly at EADS headquarters in Amsterdam.

The aerospace boss said in a weekend interview he hoped to secure contracts for the A400M in the next month, but seemed to temper his comments on Tuesday.

"I said I was hoping for the start of the summer, but it doesn't all depend on me. There is no specific calendar," he said.

"We have to reach an agreement between all seven countries."

The client countries for the Airbus transporter are France, Germany, Spain, Britain, Belgium, Luxembourg and Turkey.

The seven states, after tense negotiations in the face of production difficulties with the A400M, reached an agreement in March with EADS on sharing out 5.2 billion euros (6.4 billion dollars) in cost over-runs.

The first A400M, manufactured by EADS aircraft unit Airbus, is expected to be delivered to France in early 2013.

Gallois said in the weekend interview that tests flights were "going well" but that there remained "real technical challenges" to overcome.

Answering a shareholder question, Gallois also said that EADS could possibly deliver five Tiger combat helicopters to Germany by the end of the year.

Germany has ordered 80 of the helicopters from Eurocopter, a subsidiary of EADS, but Berlin last month slammed "serious defects" in the 11 models that have been delivered so far.

Eurocopter has said it is working on the defects and would hand over a first two helicopters to Germany for intensive tests in June and July.

"If the trials are successful, we will deliver five helicopters by the end of the year," Gallois said.

Germany has said its military "urgently" needs the combat-ready aircraft in Afghanistan, where it has deployed about 4,300 troops.