The term, “three public expenditures” or san gong jingfei, refers to government expenses for overseas trips, food and entertainment and public vehicles. The three expenditures have been considered by the general public as one of the main sources of corruption of government officials.
In May 2011, the State broadcaster Central Television Station revealed that the country's annual spending for the “three public” items was up to RMB1900 billion  [zh] in 2010, which accounts for 60% of all administrative expenses. In order to cut the spending, the Ministry of the State demanded that all 98 central government departments and offices disclose their “three public expenses”.
On 30 June 2011, the Steering Committee of the National People Congress disclosed the Central Government's “Three Public Expenditures”. The figure was up to RMB 9.4 billion  [zh] (approximately USD 1.5 billion). Despite a great deal of resistance, so far most of the 98 central government departments and offices have disclosed their spending. However, in the past two days, the Ministry of Foreign Affairs (MFA), Overseas Chinese Affairs (OCA) and the Hong Kong and Macao Affairs (HKMA) claimed  [zh] that their “three public expenditures” are State secrets.
As the Ministry of State's move towards budgetary transparency of the “three public expenditures” has very strong public support (in an opinion poll conducted in July 2011, more than 96.4% of the interviewees supported it  [zh], the pretext of “State secret” has outraged the majority of Chinese people. Below is a cartoon by Zhai Haijun showing how difficult it is to bring change to the government with the “three public expenditures” problem. (via China Media Project )
Blogger He Jun points out  that “State secret” is an excuse to protect privilege and corruption:
Lisa criticizes  the MFA for its failure in diplomacy from a nationalistic point of view:
Having spent so much money, we still lost our land. Of course the MFA dare not disclose its “three public expenditures”. However, it still dares using “State secret” to hide their shame. This is such a big lie.
In Weibo, there are a number of discussion threads about this newly invented “State secret” item. Below is a selection of immediate responses from Weibo users in the 21cbh's news thread  [zh]:
天边火林中风 外交部怎么做账的？机密开销放到三公经费里？(今天 09:32)
老狼_深圳 可笑，他们花我们的钱，我们只不过要个帐单，他们居然说这是是秘密！！！(今天 09:31)
峰回路转转路回峰 费用高了 敌对势力不就发现我们的外交很猛(今天 09:40)
李晋宁AARON 陈水扁当初也是用同样理由贪腐的，如果外交部执意不公布，那干脆就从国务院里独立出去，省得毁了一锅汤。(今天 09:39)
风一逸 国家丑闻当属国家机密，(今天 09:35)
共和一体 公款吃喝，公款出国，公款购车…为神马不能公开？除非我们养的间谍太多？？(今天 09:45)
老狼_深圳 They spend our money, all we are asking is a receipt and they dare to tell us it is a State secret!!!
峰回路转转路回峰 When enemy forces see our huge spending, they know how strong our MFA is.
李晋宁AARON Chen Shui Bian [Former Taiwan President] used the same reason to defend his corruption. If the MFA insisted on not disclosing its three public expenditures, it should be independent from the Ministry of the State, or it will ruin the whole government.
风一逸 State scandal is of course State secret.
共和一体 spending public money for banquets, travel and vehicles, why can't this be disclosed. Unless we feed too many spies.
More reactions  [zh] from the Weibo Headline news thread:
飘泊在南方的云 不公開也罷，看那些公開的又有幾份是真實帳？！(今天 11:12)
法拉盛上官 其他已经公布三公的部门郁闷了,怎么之前没想到郭家咪咪这一招(今天 10:03)
lemon5212011 除了要给国外的亲属生活费学费什么的还有养着一帮国内的杂碎，能公布吗？(今天 10:02)
法拉盛上官 Other departments which had disclosed their expenses must feel regret, how could they not have thought of using “State secret” as an excuse.
lemon5212011 They have to pay for their family's expenses and school fees aboard and feed their running dogs inside the country, of course they can't disclose the figure.
蘇奕安 the meaning of “three public expenditures” is vehicles, banquets and travel. How can that have anything to do with secrets? Are they eating and traveling with terrorist groups??