Protesters use anniversary of the handover from Britain to press for universal suffrage and elections for chief executive

Tens of thousands of Hong Kong residents endured torrential rain on Monday to push for promised democratic reforms and protest against the government. The annual 1 July march marks the anniversary of the territory's handover from Britain to China 16 years ago. But this year's protest was fuelled by anger at the unpopular Beijing-backed chief executive and concerns ranging from growing inequality to the influence of mainland Chinese in the territory.

One group carried a large banner reading "Chinese colonists, get out!" while others chanted: "One person, one foot! Kick Leung Chun-ying out!"

Organisers had hoped for one of the biggest turnouts since 2003, when half a million protesters surged onto the streets amid fury over proposed national security legislation. Supporters complained that pro-establishment groups tried to lure potential marchers away with a cheap concert and shopping discounts, but heavy rain was probably the biggest deterrent. Police said 33,500 had set out from the starting point, Victoria Park, while organisers have yet to release an estimate.

Under the "one country, two systems" framework, Hong Kong is a part of China but enjoys far greater freedoms. Beijing has promised universal suffrage for elections for the chief executive in 2017 and for the legislature by 2020. But most are suspicious of these pledges.

"The message of today's impressive turnout despite the rainy weather is clear: more Hong Kong people are demanding a faster pace and larger scope of democratic reform from the Hong Kong government, which is, however, politically sandwiched between the democrats and the central government in Beijing," said Sonny Lo, co-director of the centre for governance and citizenship at the Hong Kong Institute of Education.

"Given Beijing's distrust of the people of Hong Kong, who may really elect a chief executive independent of the centre's control, the 2017 chief executive election reform would likely be piecemeal and characterised by a nominating committee screening out 'politically unsafe' candidates."

That will not satisfy democrats, he pointed out – which would lead to the inevitable push towards the Occupy Central movement, a campaign of non-violent civil disobedience proposed for next summer if there is no real movement towards universal suffrage.

"The central government has to come up with a timetable and proposal to say how Hong Kong people can truly have one person, one vote instead of it being decided by 1,200 members of the ruling class," said Ed Chin, one of Occupy Central's organisers.

Earlier this year, a senior mainland official increased concerns by saying China would not accept a leader who confronted Beijing. On Monday, Leung said he would launch a consultation on universal suffrage "at an appropriate juncture", as he addressed a reception to celebrate the handover's anniversary.

Leung has been hit by scandals since taking power a year ago, ranging from illegal building work at his mansion to last week's fraud conviction for his first development secretary, Mak Chai-kwong.

But marcher KC Wong, who was pushing a giant red monster he had constructed, with flashing eyes and the yellow stars of the Chinese flag, said: "It's not only CY Leung that people are unhappy with: he is a puppet; it is who is behind the puppet."

The 43-year-old artist said his creation was inspired by a Japanese manga series about humans who live in walled cities to protect themselves from gigantic creatures who devour them. "Our city walls are falling one by one," he said. "You can see that in social, political and economic aspects Hong Kong is falling down – and, of course, people have asked for universal suffrage but been constantly denied."

He also complained that mainland influences were encouraging corruption and that an influx of mainland tourists was eroding local culture.

Nerissa Tsui, 21, said she was marching for the first time because issues such as housing had become so pressing. "People are living in [single] rooms, even cages, and the government says there is wealth and growth," she said.

Chau Kam-kwan and her husband Lee Siu-cheung, both retired, said they were worried about "brainwashing education" – the attempt to introduce national education courses, shelved last year after huge protests. . "We know a lot about our country, China, and love it. But we don't love this party," said Chau.

The Civil Human Rights Front, a coalition of groups which organised the demonstration, has yet to release an estimate of the number of marchers. Organisers said 400,000 people attended last year, while police put the figure at 63,000.