Japan’s prime minister, Shinzo Abe, has extended the country’s state emergency until the end of the month, amid warnings that relaxing physical distancing advice too soon could flood already crowded hospitals with coronavirus patients.

Abe declared a month-long state of emergency in Tokyo and six other prefectures on 7 April, enabling local governors to request that people avoid unnecessary trips outside and that non-essential businesses close.

The measures have since been expanded nationwide, but they are far less restrictive than those introduced in the US and parts of Europe, with no fines or other penalties for those who do not comply.

The restrictions were due to end on Wednesday – the end of a series of public holidays known as Golden Week – but Abe said at a press conference on Monday they would remain in place in all regions until 31 May. He called on people to adopt “new lifestyles” based around physical distancing, adding that the extension was “designed for us to prepare for the next step and put an end to the state of emergency”.

His decision came after after government experts had warned that the number of new infections had not fallen enough to warrant a relaxation of social distancing measures, adding that a second wave of cases could put intolerable pressure on hospitals.

The government is expected to urge residents in 13 high-risk prefectures, including Tokyo and Osaka, to continue cutting person-to-person contact by 80% and exercise other strict social distancing measures.

In prefectures that have recorded relatively few cases, restrictions on business operations and small gatherings will be relaxed, but residents will still be asked not to travel outside their home regions. Bars and nightclubs will be asked to remain shut.

Museums, libraries, parks and other facilities are likely to be allowed to reopen provided preventive measures are in place. Local leaders have voiced concern that infections could spread if people stop practising physical distancing and start moving around again.

The number of people to have contracted coronavirus in Japan stood at 15,789 on Sunday, according to the public broadcaster NHK, with 549 deaths. The figures include 712 infections and 13 deaths linked to the Diamond Princess cruise liner, which was quarantined in Yokohama, near Tokyo, in February.

The number of daily cases in Tokyo appears to have stabilised since a peak of 201 on 17 April. Japan, though, has been criticised for conducting a comparatively low number of Covid-19 tests – 1.3 per 1,000 people, compared with 12 in South Korea and 18 in the US, according to figures compiled by Our World in Data.

It has generally been testing only those showing consistent symptoms of the virus in an attempt to relieve pressure on hospitals, but that approach has made it more difficult to identify, trace and isolate people who may be asymptomatic or who are displaying only mild symptoms.

The Golden Week holidays have given an indication of how seriously Tokyoites are taking requests to voluntarily reduce contact with other people. While some central parts of the capital have been almost empty, suburban shopping areas, parks and out-of-town beaches are still busy. Some pachinko parlours have remained open, despite local authorities’ threats to name them publicly.

According to a recent survey by the Asahi Shimbun newspaper, three-quarters of Japanese said they were going out less than usual, but only just over half felt they were reaching Abe’s target of reducing contact with other people by 80%.

“The message coming from the government is rather mild, apparently trying to convey the need to stay home while prioritising the economy,” said Naoya Sekiya, a professor at Tokyo University who specialises in social psychology and risk communications. “Since people lack a shared sense of crisis, instead of staying home they’re hoping for the best and assuming they won’t get infected.”

Concern is mounting about the damage the outbreak is inflicting on the world’s third-biggest economy, which was heading for recession even before the crisis. Foreign tourism, a key component of Abe’s economic policy, has plummeted by as much as 90%, while the virus’s global spread has forced the postponement of the 2020 Tokyo Olympics.