David Cameron will travel to Brussels on Friday for talks with European Commission president Jean-Claude Juncker as his reform agenda enters a crucial period.
The Prime Minister has cancelled a planned trip to Sweden and Denmark in order to meet Mr Juncker for talks just weeks before European Union leaders are due to consider his demands for changes.
Mr Cameron hopes that a deal will be reached on his reform agenda at a summit in the Belgian capital on February 18-19, paving the way for the in/out referendum on the UK's membership of the EU.
Downing Street announced the last-minute change to the Prime Minister's schedule as a senior Brussels official insisted that the European Commission would not publish propaganda about the benefits of EU membership in the run-up to the vote but would "continue to inform citizens" about its work.
Jonathan Faull, who is leading the commission's work on Mr Cameron's demands for a new deal, came under pressure about the role the Brussels bureaucracy will play - and the taxpayers' money it will spend - in promoting the benefits of EU membership ahead of the in/out vote.
He insisted the commission will "continue to inform citizens" but will not "participate actively" or finance campaigns in the referendum.
Ukip MEP Roger Helmer said "it is an affront to democracy for foreign institutions to spend taxpayers' money in Britain seeking to influence the outcome of a British referendum" and said he did not believe Mr Faull's assurance that the commission would not produce propaganda.
Mr Faull told a meeting of MEPs from the EFDD group, which includes Ukip: "The commission will not spend a penny on propaganda in the referendum campaign.
"We do not intend to indulge in propaganda at all - I don't think we ever do, by the way - and ... we have no intention of participating directly in any referendum campaign.
"We never do, and the United Kingdom will not be different from previous ones."
But he added: "Of course, the normal business of the European Union will continue and of course the United Kingdom remains a member state of the European Union throughout this period - and I hope for a very long period thereafter."
Ukip leader Nigel Farage said that in the days before the Irish referendum on the Lisbon Treaty "from Dublin Airport to the centre of town, virtually every single billboard had been taken up by the European Commission" saying "how good EU membership had been for Ireland".
Mr Faull said: "The European Commission will, as in the other 27 member states, continue to inform businesses, citizens, consumers and so on about its activities. That is inherent in the commission's task - we are not going to close down our spokesperson service, we are not going to close down our offices in the United Kingdom.
"We will not participate actively, we will not finance campaign organisations in the referendum. We never do."