* More than 1,850 cases in Southeast Asia
* Cases have risen 10-fold this month
* Hundreds of cases linked to mosque event in Malaysia (Releads with Indonesia toll. Previous story slugged HEALTH-CORONAVIRUS/MALAYSIA)
By Stanley Widianto and Ebrahim Harris
JAKARTA/KUALA LUMPUR, March 18 (Reuters) - Indonesia's coronavirus death toll jumped on Wednesday from five to 19 and Malaysia warned of "a tsunami" of cases if people did not follow new movement restrictions as infections surged across Southeast Asia.
The number of cases across the region has risen nearly 10-fold this month to more than 1,850, driven in part by hundreds of infections stemming from a mass Muslim gathering in Malaysia just over two weeks ago.
Indonesia, the world's fourth most populous country with more than 260 million people, only announced its first two cases of the virus on March 2 despite widespread suspicions that a lack of testing concealed a bigger problem.
Its death toll jumped to the highest in the region on Wednesday, while the Philippines also recorded a rise of three fatalities to 17. Indonesia recorded its biggest daily jump in confirmed infections, by 55 to 227 cases.
Achmad Yurianto, an Indonesian health ministry official, said the number of cases was likely to rise further but authorities hoped to contain the outbreak in April.
However, Halik Malik, a spokesman for the Indonesian Doctors Association (IDI), described the increase as "extraordinary" and said "management now needs to be a pandemic management, it can't be half-hearted like it has been."
There has been criticism of the pace of testing in Indonesia with only 1,372 people tested by Wednesday - far below that of much smaller neighbours.
The World Health Organization in a statement on Tuesday called on countries in the South-East Asia region to "urgently scale-up aggressive measures to combat COVID-19".
As Malaysia imposed two-week movement restrictions, it also announced a further 117 infections. That brought it to 790 cases, although it has so far had only two deaths.
"We have a slim chance to break the chain of COVID-19 infections," Noor Hisham Abdullah, director-general of Health Malaysia, said in a Facebook post.
"Failure is not an option here. If not, we may face a third wave of this virus, which would be greater than a tsunami, if we maintain a "so what" attitude."
Nearly two-thirds of the infections in Malaysia stem from a mosque event in Kuala Lumpur from Feb. 27 to March 1 attended by pilgrims from Indonesia, Singapore, Thailand, Brunei, Cambodia and elsewhere.
Thousands of Muslim pilgrims from across Asia gathered in Indonesia on Wednesday for a similar event scheduled for this week despite fears it could also spread the virus.
"We are more afraid of God," one of the organisers, Mustari Bahranuddin, told Reuters, when asked about the risk of participants spreading the virus at the event in Gowa in Indonesia's province of South Sulawesi.
"Because everyone's human, we fear illnesses, death," he said. "But there's something more than the body, which is our soul."
Malaysia has now shut its borders for travellers, restricted internal movement, closed schools and universities and ordered non-essential businesses to stay shut for two weeks.
Hours before the movement restrictions began in Malaysia, thousands of people queued at bus stations to return to their home towns. Hordes of Malaysians who commute daily to Singapore for work crossed the border to spend the next two weeks in Singapore.
"Mass gatherings at bus terminals and then folks going all over the country from the active COVID-19 area - are we not potentially spreading it nationwide?" Malaysian physician Christopher Lee asked on Twitter.
The Malaysian restrictions are among the toughest in Southeast Asia, although the Philippines has quarantined about half its 107 million population
Thailand has announced the closure of schools, bars, cinemas, cockfighting arenas and other entertainment centres.
Indonesian police have ordered retailers to ration purchases of staple foods to contain panic buying.
Additional reporting by Rozanna Latiff, Liz Lee and Joseph Sipalan in Kuala Lumpur; Agustinus Beo Da Costa, Maikel Jefriando and Bernadette Christina Munthe in Jakarta; Writing by Matthew Tostevin Editing by Gareth Jones