Pentagon research chief Richard D. DeLauer has promised major initiatives to strengthen his much-criticized weapons-testing operation, according to a letter released yesterday.

DeLauer, undersecretary of defense for research and engineering, promised the improvements as he sought to deflate a growing movement on Capitol Hill to establish an independent testing office in the Pentagon.

DeLauer, who has lobbied hard against the proposal, acknowledged yesterday that many of the initiatives cited in his letter to Sen. John G. Tower (R-Tex.) are not new, but he said they show he is working to strengthen the program without congressional mandate.

Several recent reports and congressional hearings have criticized the Pentagon for buying billions of dollars worth of weapons without knowing whether they will work in combat. As a result, a number of senators and representatives are supporting legislation to create an independent testing office that would report to the secretary of defense and to Congress instead of to DeLauer.

"There is an inherent conflict of interest when the testing supervisor reports directly to the Pentagon official in charge of developing and procuring new weapon systems," Sen. William V. Roth Jr. (R-Del.) said yesterday.

But Roth said he welcomed the changes DeLauer promised in his letter. Without providing numbers, DeLauer promised more staff and more funds for the testing office, independent reports from the office to Congress and a vote for the testing chief on the council that advises the secretary on weapons purchases.

DeLauer said weapon testing and purchasing must be coordinated within the same agency for "maximum efficiency and cost reduction."