The BBC's governing body has been accused of "arrogance" over its response to criticism of the corporation's commercial activities.
In April the Select Committee on Culture Media and Sport criticised BBC activities that generate income, saying they were harming its competitors.
However the trust told the committee it could not answer all the criticisms as it was conducting its own review.
The MPs said this response showed an "apparent arrogance" by the trust.
In their report in April, MPs strongly criticised BBC Worldwide's purchase of the Lonely Planet, which publishes travel guides and a magazine for independent travellers.
They recommended that the BBC Trust should impose tighter controls over the BBC's commercial activities, saying they were harming its competitors and should be reined in.
The MPs said: "The purchase of Lonely Planet remains the most egregious example of the nature of BBC Worldwide's expansion into areas where the BBC has no, or very limited existing interests.
"Had the BBC Trust been a more responsible oversight body, it would have given more serious consideration to the likely impact on the commercial sector. We can only speculate as to why it did not."
The BBC Trust defended the Lonely Planet purchase but told the committee it could not respond to all the recommendations because it was conducting its own review of BBC Worldwide - and there were talks over a possible tie-up with Channel 4.
The MPs said the trust appeared to believe it had no case to answer and its response was not "coherent".
However the select committee welcomed an announcement by the trust last week, changing the governance of BBC Worldwide as the committee had recommended.