Some attempts to access the Guardian site in Beijing fail, but no clear reason for China's leadership to take issue with recent content

The Guardian’s website has been partially blocked in China, according to a censorship-tracking website.

The website was first blocked on Tuesday, according to the website greatfire.org. Numerous attempts to access the site from multiple browsers, devices and locations across Beijing failed without the aid of firewall-circumventing software. As of Wednesday afternoon local time, the Guardian’s mobile and iPad apps were still uncensored.

While users around the country have reported problems, some of those commenting below this story say they reached it without difficulty; one, using the name zangdook, said the block "comes and goes". Other users were able to access the website front page briefly but could not reload it moments later and could not reach other sections.

China's leadership is known to block websites that it deems a threat – Bloomberg and the New York Times have been blocked since 2012, when they published lengthy investigations revealing the vast wealth accumulated by the families of senior leaders.

China’s foreign ministry brushed off a question about the block at a regular press briefing on Wednesday. "This is the first time I have heard of this,” said ministry spokeswoman Hua Chunying, according to Reuters. "I don't understand the situation. You can inquire with China's relevant department."

The reasons for the Guardian block are unclear – no China-related stories published by the Guardian in the past two days would obviously be perceived as dangerous by the country's leadership. One article, published on 6 January, explores tensions in China’s ethnically-divided north-western region Xinjiang, but the Guardian has covered the subject before without any noticeable fallout.

It is also unclear whether the block is permanent or temporary. The Chinese-language versions of Reuters and the Wall Street Journal were blocked in November, but unblocked after about a month.

A Guardian News & Media spokesperson said: "Obviously we are dismayed that theguardian.com has been blocked in China. The reason for this is currently unclear but we are investigating the extent of the block and hope that access to our website will return to normal in the very near future."