BERLIN - The German Defence Ministry pushed back hard Monday against foreign criticism of a deadly German-requested air strike in northern Afghanistan and said it remains confident its commanders acted correctly.

Berlin has faced criticism for calling in Friday's strike by a U.S. jet on two hijacked tanker trucks in Kunduz province, which local officials have said appears to have killed civilians -- and for insisting that it appeared only militants were among the dozens who died.

Among the critics was French Foreign Minister Bernard Kouchner, who called the air strike "a big mistake." EU foreign policy chief Javier Solana called it "a very, very sad event."

German officials said the critics should have withheld comment until the results of NATO and Afghan investigations were available.

Defence Ministry spokesman Thomas Raabe said officials in the Kunduz region -- including its governor, intelligence chief and police chief -- wrote a letter Sunday to President Hamid Karzai in which they concluded that "only forces hostile to the government were killed" in the air strike.

Raabe said Germany's defence minister, Franz Josef Jung, spoke by phone Sunday with U.S. Gen. Stanley McChrystal, the top U.S. and NATO commander in Afghanistan.

The two agreed that the NATO investigation should move forward quickly and that "civilian victims should be avoided," Raabe told reporters. "We hope that further investigations will prove that this deployment was right. ... We continue to view it as necessary and right in military terms."

Deputy Defence Minister Christian Schmidt told ZDF television that "foreign ministers from other countries should wait for the investigations." And he questioned the efforts to date of other countries to rebuilding in Afghanistan.

Schmidt said Germany's European allies had committed to greater civilian rebuilding efforts, and asked, "How can it be that, so far, half the police who go there (to train Afghans) are Germans, and the European partners clearly need to catch up?"

Raabe said he couldn't understand comment from Solana and others "at a very early stage about a situation that was far from cleared up."

German officials have expressed fears the tankers could have been used as suicide bombs against their soldiers.

German Foreign Minister Frank-Walter Steinmeier spoke by phone Monday with his Afghan counterpart, Rangin Dadfar Spanta, Steinmeier's ministry said. The two agreed that the air strike must be investigated quickly and carefully, and Spanta thanked Germany for its "commitment in his country," a statement said.

Prosecutors in Potsdam, where the German military has its command centre, said they were considering whether to open an investigation of the officer who called in the air strike -- standard procedure when the military is involved in incidents abroad.

Spokesman Helmut Lange said it was impossible to say how long a decision might take.

The fallout comes weeks before elections Sept. 27. Conservative Chancellor Angela Merkel is being challenged by the centre-left Steinmeier, who is equally involved in Germany's Afghan mission.

Polls for some time have shown a majority of Germans opposed to the mission in Afghanistan, but the air strike has yet to set alight an election campaign that has centred on the economy. Only one of Germany's five main parties, the opposition Left Party, wants an immediate withdrawal.

Merkel's spokesman, Ulrich Wilhelm, said the chancellor would make a statement to parliament Tuesday about the air strike.

Merkel called Sunday for "a thorough and quick explanation of what took place and whether there were civilians killed." She said that "if civilians were killed, then I would naturally deeply regret that."

A security policy expert for the Berlin-based German Council on Foreign Relations, Henning Riecke, said "this is not going to turn into an election topic."

Germany has more than 4,200 soldiers in Afghanistan's relatively calm north.