China needs to ensure that risks presented by a slowing economy do not morph into social risks, the state planner said on Friday, acknowledging the problems the country faces should unemployment rise.

Keeping unemployment low is a top policy priority for China's stability-obsessed government, a task that it has admitted will become more difficult as growth grinds toward a 25-year low this year.

The government should "further improve the social security system ... to ensure economic risks do not morph into social risks", the National Development and Reform Commission said in an online statement without mentioning unemployment.

"When issuing major policies and reform measures, (the government) should insist on carrying out social stability assessments," it said.

China has no reliable official measure of joblessness, which has hovered around 4 percent in cities for 12 consecutive years.

But all official accounts suggest that the labor market has held up well and there is no anecdotal evidence of a rise in protests or unrest.

That said, the Ministry of Human Resources and Social Security warned earlier this month that it sees "structural" challenges in the labor market in the second half of the year.

Some provinces, such as the northeastern rust belt, have been hit by job losses due to their reliance on polluting businesses such as steel making and mining, which are being scaled back.

Industries such as steel and cement production have also shrunk due to supply gluts.

The transformation of large state-owned firms, resource-rich regions and old industrial towns would be stepped up to help them move up the value chain, the commission said.