MANILA (2nd UPDATE) - Eight flights were diverted to Clark International Airport on Monday due to repairs at the runway of the Ninoy Aquino International Airport (NAIA), airport officials said Monday.

Construction works for asphalt overlay had to be done on the runway, preventing aircraft from landing in NAIA, Manila International Airport Authority (MIAA) general manager Ed Monreal said.

"Nakita po namin sa umaga, maliit pa lang 'yung pot hole. Over the day, habang nagte-take off, nagla-land 'yung eroplano, 'pag dumadaan po sa pivot area ng Rapid Exit Number 3, halos nasa kalagitnaan po 'yun, doon po lumalabas 'yung mga eroplano para makalabas agad po sa taxi way, lumaki po nang lumaki 'yung overlay po natin na asphalt," Monreal said in an interview on DZMM.

He also explained that they chose to repair the runway immediately so as not to endanger passengers.

"Ayoko pong magsaalang-alang ng seguridad at 'yung safety of the passengers. Mabuti na po na magkamali kami ng konti, mag-overreact pero ayoko pong mangyari na magkaroon sila ng safety issue po. Sana maintindihan po natin 'yan," Monreal added.

The damage on the asphalt was discovered by an inspection team Monday morning, Monreal said.

According to MIAA, the crack in the asphalt overlay of the runway was 5 inches deep, 1-meter wide and 9-meters long. To avoid further deterioration, a bigger area of four meters by 19 meters will be repaired.

The repairs were expected to be completed by 10:30 p.m, he added, with the estimated time of reopening of the runway at 11 p.m.

Monreal, however, said that they will not reopen the runway as long as it is not deemed safe.

"Sana po maintindihan nila na we will not open the runway when we think it is not safe," he said.

MIAA said it will forego its regular runway cleaning from 1:30 a.m. to 3:30 a.m. in anticipation of influx of diverted flights.

Meanwhile, the following flights were diverted to Clark International Airport because of the ongoing repairs at NAIA:

Philippine Airlines flight 2080 from Catarman
Philippine Airlines flight 2890 from Ozamis
Philippine Airlines flight 659 from Dubai
Philippine Airlines flight 454 from General Santos City
2 Zest Air flights from Cebu
Cebu Pacific flight from Davao
Cebu Pacific flight from Butuan

Raymond Isip of the Clark airport corporate communications office said that before noon, some aircraft had already left Clark airport after refueling but two flights were still on standby.

Budget airline Cebu Pacific, meanwhile, asked passengers to expect delays.

Runway 06/24 closed on July19 from 1:30-6:30am due to emergency pavement repair. PAL's Pan Pacific flights affected pic.twitter.com/SAcgzNnpTC

— Jacque Manabat (@jacquemanabat) July 18, 2016

In its 2:30 p.m. advisory on Monday, Cebu Pacific asked for its passengers' understanding, saying the situation was "beyond our control."

"Due to the periodic clearing of the NAIA (Manila) runway today, some of our flights are experiencing additional delays in take-off and landing," the airline said.

Cebu Pacific said "some flights may be diverted to the Clark International Airport (Pampanga) for a temporary ground stop, before proceeding to Manila."

The airline said the following flights were also cancelled on Monday due to the runway closure:

5J 583/588 Manila – Cebu – Manila
5J 557/556 Manila – Cebu – Manila
5J 589 Manila – Cebu
5J 969/972 Manila – Davao – Manila
5J 973/974 Manila – Davao – Manila
5J 981/982 Manila – Davao – Manila
5J 703/704 Manila – Dipolog – Manila
5J 014/015 Manila – Dubai – Manila
5J 022 Manila – Doha
DG 6245/6246 Manila – Caticlan – Manila
DG 6055/6056 Manila – Busuanga – Manila

These flights scheduled on Tuesday were also cancelled:

5J 590 Cebu – Manila
5J 023 Doha – Manila
5J 039/040 Manila – Sydney – Manila