Questions have been raised over a smartphone app being developed to track potential foreign visitors' whereabouts during the Tokyo Olympics and Paralympics amid the coronavirus pandemic, due to its hefty cost and the amount of work left to do with five months to go.

Japan is to decide by the end of spring on the number of spectators at each venue and whether to accept fans from overseas. The app is seen as a disease control "lifeline," according to a games source, should overseas fans be allowed into the country.

One company, nevertheless, made and won the bid in January to develop the app for a gigantic 7.3 billion yen ($69 million) -- way before the decision is made.

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"It was made too early. There needs to be flexibility in political measures, including having alternatives," said Kanako Otsuji, a lawmaker for the opposition Constitutional Democratic Party of Japan.

Prime Minister Yoshihide Suga admitted he was "not aware of the exact figure" to develop the app when Otsuji questioned him on the outlay possibly becoming a huge waste during a House of Representatives' Budget Committee meeting on Wednesday.

But Suga also said he sees "usages away from the games too."

The app will connect with the Foreign Ministry's electronic visa and Health Ministry's HER-SYS system that share information on those infected as well as a custom system in order to centralize information on foreign visitors' movements, health condition and COVID-19 test results.

It will be compulsory for visitors to the Tokyo Games to possess smartphones and also have the app installed. In return, they will in principle be exempted from 14 days of quarantine and be free to use public transport.

But there are several concerns. It remains unclear whether it is at all possible to deny entry to people who do not have smartphones, while it is likely that the app cannot be used with smartphones developed by China's tech giant Huawei Technologies Co.

It also comes on the back of recent digital policy failures by the government.

COCOA, a COVID-19 contact tracing app, failed to alert android users that they have been in proximity to someone who has tested positive for the virus, while the use of HER-SYS has not been up to speed either.

While deeming the 7.3 billion yen an adequate investment given how much the app could save on manpower expenses, Professor Tetsutaro Uehara of Ritsumeikan University said time is running out due to its multiple link-ups with other systems.

"The workload is simply too much. It's an extremely hard schedule to establish (the app) in a short period and then to have repeated tests," he said.