MANILA (UPDATE) — The Philippines reported 259 coronavirus-related deaths on Monday, the highest in a single day, as the country's cumulative total of COVID-19 cases swelled to over 265,000.

The record-high daily tally of fatalities due to coronavirus infection was noted after 253 cases previously reported as "recovered" turned out to be "deaths" during validation process, the Department of Health (DOH) said.

The bulk of the additional deaths are from August (110 cases) and July (97 cases). The rest are from September (28), June (22), May (1) and April (1).

The number of COVID-19 cases in the country reached a total of 265,888 after the DOH announced 4,699 additional infections.

Majority or 1,498 of the new cases are from the National Capital Region, which has been the country's epicenter of the COVID-19 outbreak. Provinces that logged high number of new cases are Cavite with 221, Bataan with 198, Bulacan with 185, and Batangas with 176.

This is the 7th straight day that additional cases are more than 3,000. Before this, cases seemed to be on a declining trend, reaching just 1,000 to 2,000 a day.

Of the newly-reported cases, majority or 87% occurred in the last 2 weeks.

Last week, the DOH claimed that the “irregularly high number of cases” reported were due to laboratories catching up on delayed reporting. Although daily reporting shows that majority of the cases are from the last 2 weeks.

• ‘Irregularly high number’ of COVID cases expected this week as labs catch up on submission — DOH

The DOH said 15 laboratories were unable to submit their test results on time, for Monday’s updated tally.

The country's active cases climbed to 53,754, as total recoveries stood at 207,504 and the death toll, 4,630.

The DOH reported 249 newly-recovered patients.

There were 27 duplicate cases removed from the previous tally, including 16 tagged as recovered.

Of the 259 additional deaths reported on Monday, 253 are among the 297 cases erroneously reported as recovered by the DOH. The remaining 44 turned out to be active infections.

• DOH corrects nearly 300 ‘recovered’ COVID-19 cases as deaths and active infections

Meanwhile, the 15 labs that were not able to submit data for Monday's tally are:

1. Amosup Seamen's Hospital
2. Batangas Medical Center (MON- WED only)
3. Calamba Medical Center
4. Dagupan Doctors Villaflor Memorial Hospital
5. Daniel O. Mercado Medical Center
6. Dr. Jose N. Rodriguez Memorial Hospital and Sanitarium (TALA)
7. Eastern Visayas Regional Medical Center
8. Marikina Molecular Diagnostic Laboratory
9. Marilao Medical and Diagnostic Clinic
10. Oriental Mindoro Provincial Hospital
11. Qualimed Hospital Sta. Rosa
12. Safeguard DNA Diagnostics
13. San Pablo College Medical Center
14. Southern Philippines Medical Center
15. Tropical Disease Foundation

Experts from the University of the Philippines earlier said that the COVID-19 situation in the Philippines is improving. The UP OCTA Research group even downgraded its estimate for the total number of cases by end of September to only 310,000 to 330,000.

The Philippines logged its first confirmed COVID-19 case on Jan. 30 in a Chinese woman who arrived from Wuhan City, China where the disease is believed to have first emerged. Her male companion, tagged as the country's second case, succumbed to the disease on Feb. 1, becoming the first COVID-related fatality in the Philippines and outside China.

COVID-19 cases around the world have reached 29 million, according to the Johns Hopkins University coronavirus dashboard. More than 19.6 million of them have already recovered while 924,000 have died.