Former Foreign Office Minister Baroness Warsi says the government has "ignored" a vote by MPs that had proposed official recognition of Palestine.
Lady Warsi said she had received a "stock answer" when she raised the vote in the House of Lords.
The House of Commons voted by 274 to 12 on Monday to urge the government to "recognise the state of Palestine alongside the state of Israel".
The government said it would "judge when it is right" to make a decision.
Lady Warsi made the comments on Twitter after she had asked the government what its response would be to the "overwhelming vote".
It was the first time the Conservative peer had spoken in the Lords since quitting her post in August during the Gaza conflict. At the time, she said the government's policy on Gaza was "morally indefensible".
Responding for the government, her replacement as foreign office minister, Baroness Anelay, told peers the government would take a decision on recognising the state of Palestine "at a time of our choosing, when we think it will best bring about peace".
Baroness Warsi asked what the "specific criteria" were that would need to be met for the government to adopt the policy.
Baroness Anelay replied: "Clearly you judge criteria on a fluid system - you watch, you wait, you encourage the Middle East peace process to continue but one doesn't give up."
Baroness Warsi later tweeted: "Sadly got 'stock answer', ignored Mondays vote".
During the Lords debate, Labour's Baroness Ramsay said a "premature and unilateral" declaration of recognition would appear to be "rewarding" Palestinian militant group Hamas.
In 2012 the UN General Assembly voted to upgrade the Palestinians' status to that of "non-member observer state". Some 41 nations - including the UK - abstained.
The vote, backing the move "as a contribution to securing a negotiated two-state solution", will not decide government policy and fewer than half of MPs took part.
Conservative and Liberal Democrat ministers abstained, which is convention on motions proposed by backbench MPs.
Israel's government said the vote could undermine the chances of peace by letting Palestinian leaders think they could evade the "tough choices" needed.