SINGAPORE - Long queues formed on Monday (May 3) at four regional screening centres, as hundreds of people turned up for free Covid-19 testing offered to individuals with possible exposure to the active Tan Tock Seng Hospital (TTSH) cluster.

The Health Ministry (MOH) said last Friday (April 30) that while close contacts of the cases - a total of 35 as at Monday - have already been identified through contact-tracing, it is pre-emptively mitigating any potential risk of wider, undetected community transmission.

This includes extending free swab tests to patients discharged from - or visitors to - the hospital from April 18; as well as those who had been to or work at public places visited by cases during their infectious period.

These individuals will receive SMS messages with instructions on where to go for a government-funded polymerase chain reaction test.

From May 3 to 16, they can either walk in to a screening centre or book an appointment at a public health preparedness clinic (PHPC). The centres are the former Da Qiao Primary School at Ang Mo Kio, former Shuqun Secondary School at Jurong East, former Coral Primary at Pasir Ris, and former Bishan Park Secondary at Sin Ming.

Chinese-language daily Lianhe Zaobao reported dozens showing up at the Ang Mo Kio centre at 8am on Monday. By 11am, there were over 300 people in a line stretching 300m from the facility.

Wait times were over two hours long at Jurong East. At the Pasir Ris centre, as early as 10.30am, staff began asking those queueing up to come back another day, according to Zaobao.

Opening hours for the centres are from 9am to 12pm, and 1pm to 4pm daily.

MOH has said that individuals may be redirected to their nearest PHPC if screening centres are crowded.

It has also advised that only asymptomatic individuals go to the centres, and that those feeling ill should visit a doctor or PHPC instead.

The Straits Times has asked MOH and the Health Promotion Board - the national agency supporting Covid-19 testing - for comment.