A leading Conservative MP says he is satisfied with rules on civil servants helping anti EU ministers, after grilling Whitehall's top official.
Bernard Jenkin said he was "reassured" by Sir Jeremy Heywood's answers to his Commons committee.
Sir Jeremy told the MPs the ban only applies to "briefing and speech material supporting the Out position".
Out campaigners had criticised the move, with one minister calling the curbs "unconstitutional".
Also appearing before the Commons Public Administration Committee, the top civil servant in the Northern Ireland Office said the minister in charge of his department might have to use the Freedom of Information Act to get information.
Access to papers
The restrictions were put in place after David Cameron allowed his ministers to campaign on either side in the referendum to be held on 23 June.
The government's official position is to remain in the EU.
Sir Jeremy said officials had not been banned from supplying facts to ministers campaigning for an EU exit.
Mr Jenkin, who backs an EU exit, said he had been "reassured" by the cabinet secretary's answers - but his call for Sir Jeremy's original guidance, which had caused the row, to be withdrawn was rejected.
"It was made clear to us that whatever understandings existed before our meeting, it is now not the intention that any facts, information or papers relating to the referendum should be withheld from dissenting ministers," Mr Jenkin said.
He added: "We do think that this contradicts the cabinet secretary's letter and the Q&A briefing subsequently issued... and we suggested it should be withdrawn and re-issued, but nevertheless we welcome this clarification."
The guidance said ministers opposing the official government position that Britain should remain the EU should not be given access to government papers on the referendum or the prime minister's EU renegotiations.
Asked to clarify what it meant in practice, the cabinet secretary said "pure facts" and statistics would not be withheld from ministers.
"If there is factual material that is generally available in the department - I would have discuss that with the prime minister - but I am pretty sure he would be comfortable about that being shared."
He added: "We are not going to deny ministers information they need to run their departments."
What officials would not be allowed to do would be write speeches, prepare "arguments to use" or "rebuttal points" for ministers to use in the campaign to leave the EU, Sir Jeremy told the committee.
The idea was to prevent ministers from using government resources "to attack the government", he said.
The cabinet secretary said the guidelines were based on those that were used in 1975, when the Labour cabinet was allowed to campaign on different sides in a referendum on whether to remain in the European Economic Community.
Sir Jeremy said he had been "surprised" by the anger the guidelines had caused, adding: "I don't think there is much to see here to be honest."
Earlier, Sir Jonathan Stephens, permanent secretary at the Northern Ireland Office, told the committee his boss, Theresa Villiers, might have to use the Freedom of Information Act to to get departmental information.
Ms Villiers is campaigning for Britain to leave the EU.
Asked whether he would withhold information from her which may have bearing on the referendum, he said: "Yes. That information is to be used to support the policy of the government of the day."
Ministers campaigning for an EU exit were "operating in a personal capacity and in that respect, if they put in a freedom of information request or a parliamentary question, that will be answered, but they won't be receiving the support of the civil service", added Sir John.
London mayor Boris Johnson, who is campaigning for Britain to leave the EU, has said it would be "obviously wrong" to prevent the public from accessing any information that might inform their decision in the forthcoming EU referendum.
He added: "If there's anything that impedes public access to information about a critical decision that they need to make in a few months' time, then that's obviously wrong."
Asked if Sir Jeremy's advice was unconstitutional, as has been suggested by employment minister Priti Patel, Mr Johnson said: My general view is that we should be as open and transparent as possible and the emphasis, if at all possible, should be to get the public all the information they need to make up their decision."