WRAPUP 3-Shanghai marks COVID milestone, Beijing on edge

* Shanghai records no COVID cases outside quarantine areas

* Beijing on tenterhooks, bracing for more restrictions

* Breakthrough would mark victory for Xi in crucial year

* Infections ease as China starts Labour Day holiday

By Brenda Goh and Min Zhang

SHANGHAI/BEIJING, April 30 (Reuters) - Shanghai said on Saturday it had detected no new daily COVID-19 cases outside quarantine areas, marking a milestone in its battle to contain the virus, which has paralysed the city of 25 million and put residents in the capital Beijing on edge.

Streets in Beijing were eerily quiet at the start of a five-day Labour Day break, with residents anxious that authorities would impose further restrictions during a holiday when many typically travel or socialise.

"You look at a city that used to be crowded and now is void. You wonder how these people manage to survive," said Li, 35, who works in the finance sector in Beijing, breaking into tears.

In the eastern commercial capital of Shanghai, scenes of houses and buildings ringed with fences to prevent residents from leaving have grabbed headlines at a time when most other countries in the world are learning to live with COVID.

China maintains a zero-COVID policy aimed at eradicating the disease, leading to frustration, especially in Shanghai, where many residents have been cooped up for more than a month. Some, struggling to find food and other daily necessities, have shown rare public opposition to the government's stringent controls.

If the zero-tolerance campaign works, however, it would be a victory for President Xi Jinping's approach in a year when he is expected to secure a precedent-breaking third term.

Shanghai officials did not discuss the break in COVID transmission at their daily news conference, but social media cheered the news.

"Shanghai has finally reached zero at the community level!!! May Shanghai wake up as soon as possible!!," said one post on the Weibo platform.

Friday's zero cases outside quarantine areas in Shanghai compared to 108 for Thursday. Some, however, played down the milestone, noting that most of the city's residents were locked in some form of quarantine.

On Saturday, health authorities said there were close to 16,000 sealed-off areas in Shanghai, with more than 4 million people prevented from leaving their homes. A further 5.4 million people were blocked from leaving their compounds.

In practice, many of the remaining residents in low-risk prevention areas are still not allowed to leave their compounds.

"The city's epidemic and prevention control is currently still at a critical state, and the trend is still that people need to strengthen controls," said Zhao Dandan, deputy director of Shanghai's health commission.