Surging coronavirus cases in Southeast Asia have started affecting the supply chains of Japanese companies, with the possibility of regional production disruption becoming more real.

In Malaysia, where a lockdown has been in place since June 1, plants belonging to Toyota Motor Corp. and Honda Motor Co. remain closed. That is largely because of regulations that limit factory workers reporting to work to 10% or less.

The lockdown has already been extended twice, with more stringent restrictions imposed July 5 on Malaysia's capital region, where Japanese companies operating in the country are concentrated.