BAGHDAD, Iraq — Insurgents launched a coordinated ambush against Iraqi soldiers northeast of Baghdad on Saturday, detonating a roadside bomb and then firing on the patrol, killing 19 and wounding two, officials said.

The attack took place near Adhaim, about 60 miles from Baghdad, Iraqi officials said. It came two days after a roadside bomb killed 10 U.S. Marines and wounded 11 others on a foot patrol near Fallujah in the deadliest attack against American forces in four months.

Elsewhere, a U.S. base at Mosul’s airport came under mortar or rocket fire Saturday, wounding two American soldiers, the U.S. military said. Several detonations shook the installation — Forward Operating Base Courage — at about 6:50 a.m. the command said.

In Berlin, the German government said it was making intense efforts to secure the release of an aid worker and her driver kidnapped in Iraq on Nov. 25. In a video made public Tuesday, kidnappers threatened to kill Susanne Osthoff, 43, unless Germany stops dealing with the Iraqi government.

Foreign Minister Frank-Walter Steinmeier told reporters that ‘‘regrettably, we have not succeeded in the first week in establishing, indirect or directly, contact with the kidnappers.’’

Chancellor Angela Merkel has said Germany will not be ‘‘blackmailed’’ in the case.

Germany ardently opposed the U.S.-led invasion of Iraq and refused to send troops there. However, it has been training Iraqi soldiers and police outside the country.

The Al-Jazeera network broadcast a videotape and statement Friday in which the kidnappers of four Christian peace activists threatened to kill the hostages — two Canadians, an American and a Briton — unless all prisoners in U.S. and Iraqi detention centers were freed by Dec. 8.