A key eurosceptic has claimed victory in a battle to limit the promotion of government websites relating to the forthcoming EU referendum.

The 28-day pre-referendum period — often referred to as “purdah” — kicked in on Friday, limiting the activity of officials and special advisers in the crucial final four weeks of campaigning.

While the normal business of government can continue, there are new curbs on the support that ministers on either side of the EU debate can receive from their departments while attending outside events, on the use of government property for campaign purposes, and on government communications, including websites and social media.

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Government websites have been a particular sticking point for the Leave campaign, with Public Administration and Constitutional Affairs Committee chair Bernard Jenkin — a prominent Tory eurosceptic — concerned that links to websites setting out the government’s pro-EU position could remain in place during the “purdah” period.

Key Leave campaigners wrote to head of the civil service Sir Jeremy Heywood earlier this month, warning that continued promotion of websites relating to the vote would breach the Political Parties, Elections and Referendums Act (PPERA) and amount to “a gross violation of the spirit” of providing a fair referendum.

The new guidance (available in full below) specifically refers to websites, saying that while material that has already been published online before today “will be regarded as part of the public record and does not need to be removed from websites and social media sites”, links to those sites elsewhere “should be removed”.

It adds: “Information prepared routinely for web publication must be scrutinised to ensure it is not caught by PPERA restrictions.”

Speaking to CSW as the guidance was published, Jenkin said: “I think this is quite a climb down.  If they had been going to do this all along, they could have been much more reassuring weeks ago. It should not be necessary to badger ministers and officials into doing the right thing.”

The PACAC chair added: “It shows our legal advice was correct and they were hoping to get away with ignoring the law — law which the government would have got rid of, had we not defeated them in the Commons last September. “

Jenkin said he was still concerned, however, that “random search engine searches” could lead voters to pro-EU websites paid for by the government, and said legal advice he had received instead called for EU referendum-related material only to be made available after a specific request from a member of the public.

The PACAC chair last year led a rebellion of Tory MPs which forced ministers to keep the protected 28-day period in the run-up to the EU vote. He has been among eurosceptic MPs who have been critical of earlier restrictions on civil service support given to ministers in favour of leaving the EU, arguing that the rules put pro-Brexit ministers at a significant disadvantage in the debate.

The new rules supersede that earlier guidance, however, and make clear that both sides of the debate will now only be able to draw on civil servants for normal departmental business and not on any matters relating to the EU vote, with some logistical exceptions.

Speaking to CSW, Dr Cath Haddon — a constitutional expert at the Institute for Government think tank — pointed out that officials would still be able to provide factual briefings, fact-checking and diary support for ministers attending referendum-related events.

And she highlighted the fact that security protection for ministers will also continue, even if they are out on the campaign trail.

“Obviously that is a form of official support, but ministers who get close protection will need to continue to get that even though they’re going on a campaign visit,” she said.

“It’s similar really to the dividing line you see when ministers are doing constituency work or even during an election campaign when they’re doing campaigning work. The civil service still needs to know where they are and how that fits into with their duties as ministers. Some logistics have to cross over that boundary — you can’t really ignore where your minister is.”

Haddon said the latest guidance also differed from the rules issued to officials in the run-up to the Scottish independence referendum because it was “much more up-front” about its basis in two acts of parliament — PPERA and the European Union Referendum Act — reflecting the specific safeguards that Eurosceptics have sought ahead of the vote.

“Unlike other purdah periods, there are much more specific statutory restrictions applying this time around,” she said.

Haddon added: “The guidance does two things: it both provides clarity to those critics who are concerned that want to see fair play in terms of how government is using its resources. But it also protects the civil service. It talks about the things that civil servants should not be asked to do, so it’s quite clear that it’s trying to make sure civil servants are protected in all of this.

“Ministers and the civil service will still have to watch this and make sure that it’s not abused because it’s such a heated debate,” she said. “They will not want to overstep the boundaries of the guidance.”