The U.N. refugee agency and Rohingya community leaders in Malaysia are stepping up efforts to get refugees who attended a Muslim gathering to come forward for coronavirus checks, after cases linked to the event jumped across Southeast Asia.

More than 670 infections in the region have been linked to the gathering last month at a mosque on the outskirts of the Malaysian capital Kuala Lumpur. A total of 16,000 people of many nationalities attended the four-day event.

Reuters reported on Thursday that authorities were trying to track down an estimated 2,000 Rohingya who had attended the gathering. Rights groups said “several hundred” Rohingya attended and that the overall estimate included other refugees, such as ethnic Burmese Muslims.

Refugees are considered illegal immigrants in Malaysia and activists say they may fear coming forward for testing.

“We have increased awareness and have advised the Rohingya to get tested,” said Bo Min Naing, president of the Rohingya Society in Malaysia, estimating that 400-600 Rohingya attended the gathering.

He has been sending voice messages to fellow Rohingya on the coronavirus and urging them to get tested if they attended the Feb. 27-March 1 gathering.

Rights activist Lilianne Fan said leaders of the Burmese Muslim community living in Malaysia have agreed to get participants of the mosque gathering to present themselves for testing, though some “do fear arrest and other repercussions”.

The U.N. High Commissioner for Refugees (UNHCR) said on its website it had requested the government not to arrest any refugee or asylum seeker without documents or with expired documents as the agency had postponed all appointments, amid two-week movement curbs in the country to contain the spread of the virus.

Police did not immediately respond to a request for comment.

The UNHCR has also written to community leaders and urged them to get all refugees who participated in the mosque activities to immediately contact health authorities without fearing arrests, the leaders said.

Around 4,000 of the 14,500 Malaysia residents who attended have yet to be screened for coronavirus, the government said on Thursday.

There were 1,500 other participants from countries including Brunei, Cambodia, Singapore, Thailand, Vietnam, Indonesia and the Philippines.

“As you can imagine, given the circumstances where the healthcare systems are over-stretched at this time, we have not received any official notifications of refugees and asylum-seekers who have been infected or who have been tested,” UNHCR Malaysia told Reuters in an email.

Malaysia has 900 coronavirus cases in all, the highest in Southeast Asia, 576 of them linked to the mosque event.

Reuters