"As well as adopting vigorous safety measures, we also have to pay attention to addressing some deep-seated causes behind these problems, including dealing with some social conflicts and resolving disputes," Wen told the satellite television network that broadcasts into mainland China.

"We must strengthen the role of [dispute] mediation at the grassroots. That's something we all have to work on," he said.

Wen's remarks were the most direct yet from a senior leader on the recent assaults that have left 17 dead and scores wounded.

'Social harmony'

Al Jazeera's Melissa Chan, reporting from Beijing, said it was encouraging that stepping up security was not the only official response to the attacks.

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"They're also looking at the reasons why this is happening in order to stop the momentum of this string of killings," she said.

"It's nothing new for premier Wen to be talking about social harmony, that's a big part of his governance.

"But it is new that that he has decided to connect these two issues."

Sociologists have suggested that the attacks reflect the tragic consequences of ignoring mental illness and rising stress resulting from huge social inequalities in China's fast-changing society.

The attackers in recent cases have all been men in their thirties or forties, most of them out of work.

Triggers for the assaults have been said to be grievances over lost jobs, business failures, broken relationships, and a new home that officials had ordered torn down.

China bans nearly all citizens from owning handguns, and the attackers have used knives, cleavers and, in one case, a hammer.