Alan Duncan, the Tory health spokesman, claimed the "real" waiting lists stood more than 500,000 higher because the number of patients waiting to get on the waiting lists had almost doubled.
"These fiddled figures will fool no one. All Labour has done is shifted the bulge from waiting to an official list to waiting to get on it," he said during question time.
Earlier, the Secretary of State for Health insisted the drop was a "massive achievement" for the health service, after waiting lists rose by 11,500 in December.
The number of people waiting for treatment was 1,159,368 - the lowest figure for almost two years. The Government is now only 1,400 short of its pledge to cut waiting lists to their pre-election levels by next month, he said.
The number of people waiting more than 12 months for treatment also fell by 600 to 54,643 - the eighth consecutive reduction.