HONG KONG, March 27 (Reuters) - Hong Kong's chief executive-elect Carrie Lam met with the city's incumbent and unpopular leader Leung Chun-ying on Monday, calling for a "smooth and effective" transition of power amidst heightened tensions. Lam was chosen to be Hong Kong's next leader on Sunday amid accusations that Beijing had meddled in the election to ensure her victory and deny the financial hub a more populist leader. Many of the city's opposition pro-democracy politicians and activists were opposed to Lam's selection by a 1,200-person election committee stacked with Beijing and pro-establishment loyalists, who spurned another more popular candidate, former finance chief John Tsang "I have every confidence that we will have a very smooth transition," said Lam, after shaking hands with Leung. She said unifying society would be her most urgent task, as well as improving the relationship between the executive branch of government and the legislature including opposition democrats. Lam, the city's first female leader, will formally take office on July 1. The next few months will be critical for Leung and Lam, with Chinese president Xi Jinping expected to pay a visit on July 1 to celebrate Hong Kong's 20th anniversary of the handover from British to Chinese rule, with large protests expected. Part of the public mistrust towards Lam stems from her close working relationship with the staunchly pro-Beijing Leung, who ordered the firing of tear gas on pro-democracy protesters in 2014 during the 'Occupy' civil disobedience movement. Lam was Leung's deputy as chief secretary over the past five years, and is known as a tough, though competent administrator. Some opposition politicians, however, remained sceptical, and said Lam needed to change tack to truly narrow differences. "If Carrie Lam continues to maintain her attitude during the election period, the ignorance towards the reality and voices from the public, then I don't think she will have an easy time at the Legislative Council," said Alvin Yeung, head of the pro-democracy Civic Party and an elected lawmaker. All of Hong Kong's three other post-handover leaders have struggled to balance the demands of China's stability-obsessed Communist Party leaders, with the wish of many residents to preserve the global financial hub's liberal values and rule of law that have long underpinned its economic success. Political and social divisions have led to some legislative and policy-making paralysis and the stalling of major projects. "She has been elected pretty much solely on the support of Beijing," said political scientist Ma Ngok. "If that's the case, she might have a lot of debts that she has to repay to her supporters in Beijing."