Former Cabinet Office minister Tom Watson called on David Cameron today to ensure the contents of the Government wine cellar are made public.
Mr Watson has written to the Prime Minister asking him to overturn a Foreign Office decision not to publish full details of which wines and vintages are held in the cellar.
It is part of a long-running campaign by the Labour MP to uncover a complete database of the Government's £864,000 wine stock.
Government Hospitality, an arms' length body of the Foreign Office which manages the cellar, has published a partial list of wines in response to Freedom of Information requests but has refused to reveal vintages for commercial reasons.
It has argued that publishing a full stock list would prevent the Government being able to buy wine at a discount from suppliers and could cause "undue influence" in the wine market.
In his letter to the Prime Minister, West Bromwich East MP Mr Watson said the Foreign Office had refused to conduct an appeal against its decision not to publish the full contents within the recommended 20 days.
Comparing the situation to Mr Cameron's veto of health minister Anne Milton's proposal to scrap free school milk, he wrote: "You say we live in the new age of transparency. Yesterday you overruled the Department for Health. If you mean what you say, today you will overrule the Foreign Office.
"All I ask is that the public are allowed to know the contents of the ministerial wine cellar."
In June it emerged that £18,000 had been spent topping up the wine cellar since the General Election, bringing the total value to £864,000 and leading Mr Watson to call for the entire collection to be sold off to raise money.
High-profile wines from the likes of Chateau Latour, Chateau Lafite, Chateau Margaux and Chateau Mouton Rothschild are among the bottles in the cellar used for entertaining VIP guests at departmental banquets.
The Foreign Office has said Government hospitality spending is "under review".