China has suspended or closed the social media accounts of more than 1000 critics of the government's policies on the COVID-19 outbreak as the country moves to further open up.

The Sina Weibo social media platform says it has addressed 12,854 violations including attacks on experts, scholars and medical workers and issued temporary or permanent bans on 1120 accounts.

The ruling Communist Party has largely relied on the medical community to justify its harsh lockdowns, quarantine measures and mass testing, almost all of which it abruptly abandoned last month, leading to a surge in new cases that have stretched medical resources to their limits.

The party allows no direct criticism and imposes strict limits on free speech.

The company "will continue to increase the investigation and clean-up of all kinds of illegal content, and create a harmonious and friendly community environment for the majority of users", Sina Weibo said in a statement.

Criticism has largely focused on heavy-handed enforcement of regulations, including open-ended travel restrictions that saw people confined to their homes for weeks, sometimes sealed inside without adequate food or medical care.

Anger was also vented over the requirement for anyone who potentially tested positive or had been in contact with such a person to be confined for observation in a field hospital, where overcrowding and poor food and hygiene were commonly cited.

The social and economic costs eventually prompted rare street protests in Beijing and other cities, possibly influencing the party's decision to ease the strictest measures.

As part of the latest changes, China will also no longer bring criminal charges against people accused of violating border quarantine regulations, according to a notice issued by five government departments on Saturday.

Individuals in custody will be released and seized assets returned, the notice said.

The adjustments "were made after comprehensively considering the harm of the behaviours to the society, and aim to adapt to the new situations of the epidemic prevention and control", the official China Daily newspaper website said.

China is facing a surge in cases and hospital admissions in major cities and is bracing for a further spread into less developed areas with the start of the Lunar New Year travel rush, set to get under way in coming days.

While international flights are still reduced, authorities say they expect domestic rail and air journeys will double over the same period last year, bringing overall numbers close to those of the 2019 holiday period before the pandemic hit.

The Transportation Ministry on Friday called on travellers to reduce trips and gatherings, particularly if they involve elderly people, pregnant women, small children and those with underlying conditions.

People using public transport are also urged to wear masks and pay special attention to their health and personal hygiene, vice minister Xu Chengguang told reporters at a briefing.