David Cameron's pledge would go further than this by including all meetings (not just hospitality) for special advisers and - significantly - by also covering permanent secretaries, the top grade of the civil service.
Assembly government officials are part of the UK civil service and its top official, Permanent Secretary Dame Gillian Morgan, is accountable to the UK Cabinet Secretary Sir Gus O'Donnell.
Earlier the Iranian Ambassador met at the Foreign Office with the FCO's top civil servant and permanent under secretary, Peter Ricketts, to discuss the situation.