HONG KONG (AFP) - One of China's most powerful officials tells Hong Kong he brings a "caring heart", in a conciliatory start to a visit on Tuesday (May 17) that has stirred anger in a city that resents Beijing's tightening grip.

The three-day trip by Mr Zhang Dejiang, who chairs China's communist-controlled legislature, is the first by such a senior official in four years and comes as concerns grow in semi-autonomous Hong Kong that its long-cherished freedoms are under threat.

While Mr Zhang is ostensibly visiting to speak at an economic conference on Wednesday, the trip is widely seen as a bid to take the temperature in an increasingly divided city with a fledgling independence movement.

The visit has infuriated opponents, critical of a massive security operation that includes barricading protesters into designated areas out of Mr Zhang's sight.

Wednesday will see several pro-democracy groups rally, with some activists saying they will try to get close to Mr Zhang.

Mr Zhang arrived just before noon at Hong Kong airport where he was met by the city's leader Leung Chun Ying and a brass band.

In a short speech on the tarmac, he said he brought a "caring heart" from the Chinese central government as well as "hearty greetings and good wishes" from China's President Xi Jinping.

He noted there was "very nice weather" in both Beijing and Hong Kong, and said he would look at the work of the Hong Kong government and the changes in the lives of city residents.

He also pledged to listen to a variety of political views. "(I will listen to) people from all walks of life about any suggestions and demands regarding the implementation of 'one country two systems'," said Mr Zhang, referring to the semi-autonomous system under which Hong Kong is governed since being handed back to China by Britain in 1997.

He also said he would listen to "any suggestions and requests regarding the nation and Hong Kong's development".

Mr Zhang will meet a group of veteran pro-democracy lawmakers on Wednesday evening, a rare move observers say is designed to defuse frustrations over stalled political reform.

"It is really time for him to meet with non-establishment legislators... to hear our analysis of how Hong Kong ended up where we are today, and what are the ways forward," Civic Party lawmaker Alan Leong, who is part of the invited group, told AFP.

However, only four pro-democracy legislators will meet Mr Zhang, and protest groups voiced anger they were being kept away from the harbourfront conference centre where he will speak.

"Zhang Dejiang is coming here to understand the situation in Hong Kong but now his eyesight will be completely blocked," said Mr Sham Tsz-kit of Civil Human Rights Front.

Layers of large, water-filled plastic barricades cordoned off roads in the area and paving stones have been glued down to prevent protesters using them as missiles.

That comes after demonstrators levered up bricks during running battles with police in February.

Police are even patrolling Lion Rock - a hill on the other side of the harbour where pro-democracy protests banners have regularly been unfurled.

However, activists still managed to hang a banner calling for universal suffrage on a nearby hillside on Tuesday morning.

Another, demanding the "end of Communist Party dictatorship" was hung on a highway from the airport into the city.

A small group of pro-democracy protesters, including student leader Joshua Wong, chanted and held up signs calling for universal suffrage and self-determination near Mr Zhang's hotel as he arrived.

High-profile democracy activist Nathan Law tried to breach the barricade and was tackled to the ground by police.

In a message posted on Facebook, Mr Law said the protest was to "deliver a message that we are willing to confront authorities as Hongkongers have dignity".

There was also a rival group of pro-China demonstrators, who waved national flags.

Hong Konger Jimmy Tso said he had come to "show his support for Mr Zhang".

The visit is expected to help Beijing gauge whether city leader Leung should stand for another term - his current stint ends in March 2017.

Like all Hong Kong leaders, Mr Leung was chosen by a 1,200-member committee stacked with Beijing loyalists.

Mass rallies in 2014 for fully free leadership elections failed to win political reform.

Since then, young campaigners have become increasingly frustrated with intransigence in Hong Kong and Beijing, with some suggesting they might use violence to force change.

Hong Kong has been semi-autonomous since it was handed back to China by Britain in 1997, with freedoms unseen on the mainland.