Germany cancelled plans to purchase and modify US-made Global Hawk surveillance drones because it believed that European authorities will not certify them to fly in civilian airspace.
The opposition Social Democratic Party (SPD) and the Green party have charged that de Maiziere knew long before that the 'Euro Hawk' will not get the flight permission for the European airspace, but withheld that information from the parliamentary defence committee until last week.
The defence ministry is also facing allegations that it had denied the Federal Accounting Office access to vital documents on the 'Euro Hawk' project.
The accounting office, which has been auditing the project since the beginning of last year, was not given all the documents it had asked for and in some cases documents were given only after making certain passages unreadable, its officials were quoted as saying in media reports.
More From This Section
"The defence ministry's handling of the Euro Hawk project smacks a cover up," defence policy spokesman of the Green party in the Bundestag Omid Nouripour said.
Rainer Arnold, defence policy spokesman of the SPD said it was a "breach of trust" that the "massive technical problems" of the 'Euro Hawk' project, which are known to the defence ministry since the end of 2011, were withheld from the defence committee.
He demanded the minister to thoroughly explain the cancellation of the drone project and to "take the necessary consequences.
Maiziere has not reacted to the allegations against him, but his office announced that he will make a detailed statement on the 'Euro Hawk' issue at the next meeting of the Bundestag defence committee on June 5.
It has the capability to carry a payload of 1,360 kg and to remain airborne up to 40 hours at an altitude of 20 kilometres.
One 'Euro Hawk' was delivered to the German army by the US aerospace company Northrop Grumman, which built the unmanned aircraft on an order from the German Defence Ministry.
Along with the scrapping of the project, the ministry also cancelled the order for four additional drones at a cost of 520 million euros (UDSD 676 million).