Questions have been raised about whether the Government is doing enough to help smaller firms after it was accused of "losing momentum" in efforts to give them more business.
The Public Accounts Committee said that while the Government reported progress has been made on targets to spend more with small and medium-sized enterprises (SMEs), larger companies still dominated orders.
The committee questioned whether the voice of SMEs was being heard in government, adding it was not convinced that increased spending was being given enough priority.
Meg Hillier, who chairs the committee, said: "We are sceptical about just how much progress has been made on increasing spending with SMEs.
"The fact the Government has changed its approach to measuring such spending in four of the last five years makes it impossible to properly assess performance.
"The Government has now committed to an ambitious, higher target for SME spending and there is clearly work to be done if that target is to be achieved. It's a simple point, but launching initiatives is not the same as delivering results.
"The Government's pledge to increase SME spending will have been welcomed by those who stand to benefit but without new and concerted action there is a real risk it will not be honoured."
Some government initiatives have stalled or stopped altogether, added the committee.