In the letter, published today, the committee calls on the government to rethink its rejection of key proposals for how the committee and the government could work to enable effective scrutiny of treaties, including trade agreements.

The letter highlights that commitments made by a minister at the despatch box appear to have been watered down. These included a promise to facilitate a debate on negotiating objectives if requested by the committee. The minister also stated that he could not envisage a new future trade agreement proceeding to ratification without a parliamentary debate having first taken place. The government now describes these commitments merely as a “firm ambition”, indicating that undefined “other factors” may have to be considered. If government commitments made at the despatch box cannot be relied on, this would be of great concern, not just to the committee, but to both Houses.

The letter calls for commitments made by ministers on the scrutiny of trade deals to be documented, providing a clear framework to allow agreements to receive consistent scrutiny. This has the support of the House of Commons International Trade Committee.

In its report, the International Agreements Committee had also asked to be given notice of when other, non-trade related agreements were about to be laid in Parliament – a proposal the government has refused.

The committee additionally recommended that substantive changes to international agreements and any significant political deals called “memoranda of understanding” (MoU) be deposited with Parliament for scrutiny. The letter emphasises that without predictable criteria for such amendments or MoUs to be laid before Parliament, scrutiny will effectively become optional.

Baroness Hayter, chair of the House of Lords International Agreements Committee said: “I strongly urge the government to reconsider its response to my committee’s report Working Practices: one year on, on the scrutiny of international agreements.

“Arrangements for scrutiny need to be clear and transparent. The watering down of previously made commitments on trade deals and the rejection of pragmatic recommendations, such as that there should be a single written record of all commitments in respect of scrutiny of trade agreements, is deeply concerning.

“The government also refused to address the absence of clear criteria for when Memoranda of Understanding and amendments to existing treaties should be deposited in Parliament. Or even to give the committee advance notice of pending agreements.

“When the government does not constructively engage with committees, the effect is that parliamentary scrutiny becomes less effective and democracy suffers.

“We invite the government to provide assurances that previous commitments will be respected and recorded in an exchange of letters; and for it to engage constructively both with our committee and with any other relevant parliamentary committees. Doing so will lead to stronger, fairer international agreements, to the benefit of all.”

Angus Brendan MacNeil MP, chair of the House of Commons International Trade Committee said: “My committee previously endorsed the International Agreements Committee’s Working Practices report, and we were very disappointed to see the government’s rejection of the recommendations and our additional suggestions.

“The government must stay true to the commitments it has made to Parliament, and we must be able to trust that ministers will not walk back on their promises down the line. Our committees play a vital role in the scrutiny of new free trade agreements, and to do this thoroughly, we need to know future scrutiny arrangements in advance – it is not enough to say “now is not the right time”.

“I will shortly be writing to the Secretary of State for International Trade to make these points more fully, emphasising our support for the recommendations and the need for government to enable strong scrutiny arrangements to be planned and delivered.”