The 689 new cases were the most since 533 were reported on Saturday.
The country has recorded 1,028 deaths.
The spike comes as the government is considering a plan to start easing social restrictions next month to allow businesses to gradually reopen.
The plan, still under development, aims to restore "business as usual" by the end of July.
Shopping malls would resume limited operations on June 8, which may be followed by a staggered reopening of schools.
The economy grew just 2.9% in January-March, down from 4.99% a year earlier and its slowest expansion in almost two decades.
The draft plan states it is contingent on reducing the increase in new cases. (AP) SCYSCY