China has ordered a probe into the toxic river spill that led to millions of people having their water supplies cut for several days. The government has also apologised to Moscow for the pollution, which is heading towards the Russian border city of Khabarovsk. The accident could cause political damage as well as physical harm

A PUBLIC apology from China is an exceptionally rare event. But as a slick of toxic water makes its way along the half-frozen Songhua River towards the Russian city of Khabarovsk, the country's leadership is saying sorry. This is not, however, to be read as a sign of an imminent end to the secretive culture that for days attempted to cover up one of China's worst ever pollution spills into its waterways.

The November 13th discharge of some 100 tonnes of benzene and nitrobenzene from a petrochemical plant in the north-eastern province of Jilin could end up causing political damage as well as physical harm. So far, at least, no casualties have been reported, apart from five people killed in the explosion that created the slick (though local officials have a great incentive to cover up such details). On Sunday November 27th, officials in Harbin, capital of the neighbouring province of Heilongjiang, reactivated the city's water supply after the slick passed by without major incident. The chemicals can be very dangerous if inhaled or ingested in sufficient concentrations. To reassure jittery residents, the provincial governor, Zhang Zuoji, was shown on television drinking a glass of tap water pumped from Harbin's stretch of the river (which is hardly clean at the best of times but is now at least said to have safe levels of the leaked chemicals).

But as the 80km (50-mile) slick moves on downstream towards Khabarovsk, 700km to the northeast, where it is expected to arrive by early December, there could be significant political fallout. China's prime minister, Wen Jiabao, visited Harbin on Saturday, four days after the city had turned off all tap water to prevent contamination. As many residents queued for water delivered to neighbourhoods by truck, Mr Wen pledged that investigations would be conducted to determine responsibility for the disaster.

PetroChina, a giant state-controlled company listed on the New York and Hong Kong stock exchanges, has apologised for the explosion at a factory run by Jilin Petrochemical, a subsidiary. Officials in Jilin, who kept quiet for days about the slick, have also said sorry. So too has China's foreign minister, Li Zhaoxing, to Russia's government. But officials in Harbin have been defensive about their decision, even after they discovered the approaching threat, to keep the spill secret from residents until the last minute. At first they said the water supply would be turned off for “maintenance”.

China has a habit of dishing out blame after big accidents, but remains unwilling to address the culture of secretiveness that can aggravate such problems. Last year, PetroChina's chairman, Ma Fucai, stepped down following an accident at one of his company's plants in the south-western city of Chongqing in December 2003, which killed more than 200 people in a cloud of hydrogen sulfide gas. Earlier that year, the mayor of Beijing and the health minister were sacked for mishandling an outbreak of SARS, an often fatal respiratory disease. Yet despite official admissions that the disease could have been better controlled if the public had been informed more promptly, Chinese officials have been reluctant, at least until very recently, to be fully open about the spread of bird flu.

It is highly unlikely that those sacked during the SARS outbreak were as responsible as they were portrayed to be. Higher-level officials were almost certainly just as culpable, but were spared because of their rank. What is unclear in the case of the Songhua River incident is whether the central authorities were aware of the extent of the problem before it was finally revealed last week. The prime minister did not openly apologise for any central-government failings during his visit to Harbin. The likelihood is that blame will mainly be apportioned lower down the line.

As during the SARS outbreak, China's state-controlled media have been unusually feisty in their criticisms of the way news about the river pollution has been handled. In 2003, some optimists believed that China would emerge from SARS with a government less inclined to knee-jerk secrecy and possibly more tolerant of media exposure of its shortcomings. Many Chinese journalists say they have been disappointed. As the slick moved along the Songhua river towards Harbin, it passed through Songyuan, a big city in Jilin, without a word of warning being issued to the public (though water supplies were suspended). It may be a long time before there is a full accounting of any harm done.