Ministers are under growing pressure to share the documents from Peter Mandelson’s vetting process with the parliamentary committee tasked with deciding if they should be made public.

In February, MPs passed a binding parliamentary motion, known as a humble address, requiring the government to publish “all papers” relating to Mandelson’s appointment as ambassador to the US.

The motion made an exemption for documents “prejudicial to UK national security or international relations”, which would be given to the Intelligence and Security Committee, a trusted nine-person group of MPs and peers who oversee the activities of the intelligence agencies.

Officials within the Cabinet Office have discussed for weeks how to comply with the terms of the humble address because it would be “unprecedented” to disclose details of Mandelson’s developed vetting process.

As the Guardian revealed last week, United Kingdom Security Vetting (UKSV) decided that Mandelson should be denied clearance but that advice was overruled by the Foreign Office so he could take up his post.

At the heart of the controversy are two documents. The first was produced by UKSV setting out its conclusion and explaining why it ranked Mandelson a “high concern”. The Cabinet Office on Friday published a template of that file on its website.

The second is a highly confidential document produced by the Foreign Office in which it explained its decision to overrule UKSV.

Some officials have been in favour of disclosing the documents to the ISC to comply with parliament’s wishes. According to a government source, Cat Little, the permanent secretary in the Cabinet Office, was in favour of the outcome of the UKSV decision being made public and the relevant documents being disclosed, in full and unredacted form, to the ISC.

However, others in officialdom have been opposed to disclosure, citing, among other issues, the risk to national security. Such was the extent of concerns over risks of disclosure that senior officials, including Little, knew about Mandelson’s vetting failure but did not inform Keir Starmer, the prime minister, for several weeks.

Amid an impasse, there were fears among at least some officials that there might be a cover-up and the documents would never see the light of day. After the Guardian’s revelations last week, it seems inconceivable that the documents will not be disclosed, but there are still concerns there may be delays and obstacles.

Alex Burghart, a Conservative shadow minister, told the BBC’s Sunday with Laura Kuenssberg that MPs had instructed the prime minister to hand over “all of the documents associated with this” two months ago.

He said: “We understand that No 10 are trying to work out whether they should release documents under the humble address. That’s not what parliament said. Parliament said hand it over and if it’s sensitive, it should go to the ISC. Once again this government is not doing the right thing. The only reason this has come out now is because of investigative journalism.”

The ISC is expected to meet in the coming days, with Little likely to face questions from its members.

A spokesperson for the government said it was “committed to complying with the humble address in full as soon as possible”. They added: “Any documentation within the scope of the humble address that requires redaction on the basis of national security or international relations will be provided to the ISC. This will include documents provided to the Foreign Office by UK Security Vetting.”