Even as Xi Jinping was unveiled as China's new leader, clues on who will take over from him a decade down the line in the long-planned Communist succession system were already being revealed.

Analysts say the front runners for 2022 are Hu Chunhua, a literature graduate who cracked down on protestors in Tibet, and Sun Zhengcai, who spent time as an agricultural researcher in the British countryside.

The two men, both 49, were named to the all-powerful 25-strong Politburo, the nation's second most powerful committee, after last week's pivotal Communist Party congress.

Many believe they are now headed for the inner circle of Chinese politics, the seven-member Politburo Standing Committee which Xi is expected to lead for the next decade.

Xi's own ascension had been expected since 2007, when he was given a position on the standing committee.

Aside from Xi and number-two Li Keqiang, its other members will have to step aside at the next congress in 2017 after they reach retirement age, clearing the way for the next generation to step up.

At the same time Hu and Sun's Politburo colleagues are all significantly older, meaning many will be out of the running for the highest posts in 2022.

"There is a big possibility that both will become China's top leaders in 10 years time as they are the youngest on the Politburo," said Zhang Xin, a political scientist at People's University in Beijing.

"They are in good position for advancement, but they still have to prove themselves in the coming years."

China's choreographed Communist successions are a start contrast to the boisterous elections of Western democracies, and critics say they are out of place in a fast-modernising society with aspirations for greater transparency.

"Today, China still has not been able to leave behind authoritarianism, power monopolies, rampant corruption... the root of these weighty social problems is autocracy," rights lawyer Xu Zhiyong said in an essay ahead of the congress.

But in recent decades the system has enabled China to avoid the frequently violent political purges that were routine during the rule of Mao Zedong, and the continuity has also been a part of the nation's economic transformation.

"The party over the last 20 years has sought to institutionalise a smooth and predictable leadership transition," said Joseph Cheng at City University of Hong Kong.

Hu, currently the party leader in Inner Mongolia, comes from a poor background and cut his teeth cracking down on anti-Beijing demonstrators in Tibet in the late 1980s along with outgoing president Hu Jintao, who was then party secretary for the region.

Although they are not related, the younger Hu has long been seen as a protege of his namesake, so much so that he has been dubbed "Little Hu".

Tibetans regularly protest against what they say is marginalisation and discrimination by Beijing, and the party congress was marked by a spate of self-immolations. Maintaining stability is a key issue for the Communist Party.

"Hu Chunhua has shown that he can handle ethnic relations and has made achievements in maintaining ethnic unity," said Zhang.

"You can say that he has good experience and has made results in cracking down on separatism... the strict way he has handled separatism is an important part of his political achievements."

Sun's promotion to the Politburo is largely based on his expertise in agriculture -- a key sector in a country that needs to feed 1.3 billion people.

He graduated from Beijing Agriculture University in 1987 and later spent a year as a visiting scholar at Britain's Rothamsted Experimental Station, which is based at a manor house in the Hertfordshire countryside north of London.

Later he served as minister of agriculture for three years.

"This means that the party is employing experts in top posts and not just people with strong political backing," said Cheng.

Chinese politics is highly factional and getting ahead has usually depended on receiving sufficient support from the right backers while not overly alienating rival camps.

Hu Jintao backs both men's promotions, Cheng added, while Sun is also believed to have connections to octogenarian former president Jiang Zemin who is seen as a kingmaker after a surprise political comeback.