Former Hong Kong finance chief John Tsang has announced that he will compete in the race to be the city's next chief executive, promising to unite and "rekindle hope" for the increasingly divided city.

Mr Tsang, 65, became the fourth person to join the race when he announced his candidacy yesterday, joining former chief secretary Carrie Lam, 59, lawmaker Regina Ip, 66, and retired judge Woo Kwok Hing, 70.

Nicknamed Mr Pringles for his resemblance to the mascot of the crisp brand, Mr Tsang has been leading in popularity polls since he showed interest in the city's top job last July.

An election committee of 1,194 members will choose the city's next leader on March 26, after Mr Leung indicated last month that he would not seek a second term.

At a press conference yesterday, Mr Tsang likened today's Hong Kong to be facing "a great time of uncertainty" like in 1982, when Britain started negotiating with China on the city's future.

He added that he is saddened to hear people thinking of emigrating, just like before.

Many Hong Kongers had left the city then due to fears over what would happen after the former British colony was handed back to China in 1997.

"It made me wonder what the reason was that they think like that and what I could do," he said.

Describing the city as being at a "historic juncture", Mr Tsang said he wanted to stem emigration.

He reckoned that it will not be an easy task with the city struggling to grow amid rising polarisation, confrontations and calls for independence. "We do need to check the disruptive elements that threaten to curb our growth. The anger, the polarisation, the occasional irrational talks of independence and the confrontation that has torn our society apart," said Mr Tsang.

Seen to be more moderate than incumbent chief Leung Chun Ying, Mr Tsang will likely face stiff competition from Mr Leung's former deputy, Mrs Lam, who is seen as Beijing's favoured candidate.

Analysts cite how Mrs Lam's resignation from her government was approved by Beijing within days, while it took about a month for Mr Tsang's resignation to be approved.

Asked to compare himself with his former colleague, Mrs Lam, Mr Tsang said: "Carrie is a very serious and hard-working civil servant... We worked in the government for a long time, but we took care of different aspects of policies. So, it is a bit difficult to make a comparison."

In a speech at the press conference, Mr Tsang recalled emigrating to New York from Hong Kong with his family when he was 14. "The life of Chinese and ethnic minority immigrants was not easy," he said.

He moved back to the city with his wife and two children in 1982 and joined the civil service under the encouragement of Mr Donald Tsang, who was later the city's second chief executive.

The two men had met at Harvard University, where Mr John Tsang was studying for a master's degree in public administration.

After serving in the civil service for 34 years and having the chance to engage with people from all walks of life, Mr John Tsang proudly declared: "I know Hong Kong. The situation in Hong Kong today cannot be resolved by mere force and aggression, it requires restrain."

The government needs to review the city's social and economic policies to face global changes, he said.

"Instead of acting against market forces, we should remedy market pitfalls," he said, adding he agreed with Mr Leung's direction in housing policy and will continue to seek more land to build more homes.

Yesterday, Mr Wu Chi Wai, chairman of the liberal Democratic Party, said he has higher expectations of Mr Tsang than Mrs Lam and is waiting to hear how he would solve the city's problems.