The inability of defence officials to answer questions posed by senators is infuriating the opposition.

Liberal senator Russell Trood is a key member of a foreign affairs, defence and trade committee who routinely uses the Senate estimates process to quiz officials.

The most recent estimates hearings were held on March 3 and answers taken on notice were due on April 21.

"This is not the first time defence has proven reluctant to provide answers," Senator Trood told AAP on Thursday.

"They were equally sluggish after the last estimates hearings."

The questions asked by Senator Trood and the other senators who wander in and out of hearings that often run late into the night range from the mundane and very technical through to issues affecting frontline soldiers.

"For the second time in six months, we are less than two weeks away from the next round of estimates hearings, and defence has failed to answer a single question placed on notice," Senator Trood said.

He pointed to Defence Minister Stephen Smith's order that departmental media officers improve their own deadline management.

"It seems to me, he ought to consider requesting similar advice on ways to improve the pace with which it responds to questions from the Senate," Senator Trood said.

http://news.ninemsn.com.au/national/8248367/defence-where-are-the-answers