China's economic growth can only continue if the country reforms, said its expected next premier and newly promoted Communist Party number two Li Keqiang, according to state media Friday.

The ruling party's new leaders -- who were installed after a key congress last week and will also assume top government posts in March -- took charge in the face of slowing growth, rising popular discontent and calls for reform.

"Reform and opening is essential to allowing people to enjoy a better life," the China News Service quoted Li as saying while meeting officials overseeing 11 cities and provinces that are test-beds for reforms.

"If we don't do it, then we won't make mistakes, but will bear historic responsibility," he said Wednesday, in some of his first remarks since moving up the hierarchy.

Li focused on social and economic -- rather than political -- development, singling out uneven growth and the rural-urban imbalance as problems, both of which have generated popular resentment.

Strict residency rules needed to be fixed, as did land management and the social service system, he said, without giving specific details.

China's leaders have repeatedly promised reforms.

Li also warned that economic growth was likely to slow from the double digits of past years to around seven percent annually, but added that it would still be possible to achieve a "moderately prosperous" society by 2020.

Analysts say that as vice premier Li has been at the forefront of efforts to pursue more balanced development, although the record has been mixed.

Some say that with no broad power base, he may have trouble effecting major change in the face of the party's consensus-based leadership, vested interests and provinces bent on growth.

The Chinese word for reform is made up of two characters, both meaning change, and the China News Service said: "If there were two characters to summarise Li Keqiang's speech at the conference, they would be reform.

"To describe it in four characters would be, without a doubt: reform, reform. And to describe it in six would be: reform, reform, reform."

China's incoming leaders also face mounting pressure to tackle official corruption, highlighted by Xi Jinping when he took over as the new party chief last week.