Beijing has suspended the release of industry-specific data from a monthly survey of manufacturing purchasing managers, with an official saying there was limited time to analyse the large number of responses.
"We now have 3,000 samples in the survey, and from a technical point of view, time is very limited - there are many industries, you know," Cai Jin, vice-president of the China Federation of Logistics and Purchasing, which compiles the data with the National Bureau of Statistics, said yesterday in Beijing.
The disappearance of data on industries including steel adds to issues hampering analysis of the world's second-biggest economy, after fake invoices inflated trade numbers this year.
The Purchasing Managers Index also omitted readings on export orders, imports and inventories without any explanation from the government.
"Suspension of the monthly data, without prior notice, makes the research work difficult for us," said Xu Xiangchun, a steel researcher and chief analyst at Mysteel.com 
"The random absence of official data is disorienting."
The industry-specific PMI readings have only been available via paid subscription, while the broader data is issued via press releases.
Ding Shuang, senior China economist at Citigroup in Hong Kong, said earlier this week that he subscribes to the industry-specific PMI readings, and the logistics federation told him in a July 1 e-mail that the figures would be "temporarily" suspended and no reason was provided.
Cai said the suspension was not permanent. He did not elaborate on the reason for the decision beyond rejecting the idea that it was because the data showed too much weakness.
The statistics bureau did not respond to e-mailed or faxed questions seeking comment.
The logistics federation increased the number of companies in its manufacturing survey to 3,000 from 820 starting with January's reading and also regrouped industries into 21 categories from 31. The latest release referred to 31 industry groups.
Less information makes it more difficult to assess the magnitude of an economic slowdown at risk of deepening because of a cash squeeze in the interbank market that sent borrowing costs soaring last month.
A person involved in producing PMI data on the mainland's steel industry said the release was suspended after the statistics bureau decided to change how the figures are compiled.
It is not yet clear what changes will be made and in what time frame, or if the data for this month will be released next month, said the person, who asked not to be identified.