WASHINGTON — Defense Secretary Donald Rumsfeld, invoking emergency powers, has authorized the Army to grow temporarily by 30,000 troops above its congressionally approved limit of 482,000 to facilitate a restructuring of forces severely strained by operations in Iraq and Afghanistan and counterterrorism missions elsewhere.

The increase, disclosed Wednesday in congressional testimony by Gen. Peter Schoomaker, the Army’s chief of staff, surprised members of the House Armed Services Committee, many of whom have been pressing for a larger Army.

Rumsfeld has resisted a permanent increase for months, arguing that a number of efficiency measures and restructuring moves could alleviate some of the stress on U.S. forces. But his approval of a temporary rise — which does not require congressional action and which Schoomaker said would probably be needed for four years — appeared to acknowledge that some relief is needed.

Schoomaker said the increase would make possible his plans to restructure the Army by expanding the number of brigades and creating more agile, deployable forces. Money for the added troops, he said, would come from the $87 billion emergency spending bill for Iraq and Afghanistan that passed in November.

An aide to Schoomaker said after the hearing that the troop increase probably would be achieved through incentives to keep soldiers from leaving once their contracts expire and through "stop-loss" orders barring their exit.

Schoomaker also disclosed that he has ordered his staff to plan for how the Army, which is now replacing its forces in Iraq with an entire set of fresh units, would rotate another force of similar size into Iraq in 2005 — and again in 2006. But other Pentagon officials said any decisions on the size of future rotations are months away.