MANILA - The country's infrastructure chief apologized Wednesday amid reports that a road barrier failed to stop a passenger bus from plunging down a cliff in Carranglan, Nueva Ecija.

At least 30 people were killed when a Leomarick Bus fell down a 100-foot ravine in Carranglan's Capitalan village on Tuesday.

Capitalan barangay captain Laberto Villa said there should have been stronger road barriers and more prominent safety signs at the crash site.

Public Works and Highways Secretary Mark Villar said the cement railing in Carranglan follows international standards and is supposedly the strongest type of barrier.

The barrier, he said, may have collapsed because it was rammed head-on by the bus, which was possibly overloaded.

"Ang alam ko itong railing ang pinakamatibay na railing... Nalulungkot din ako and I'm sorry. I apologize. Nakakalungkot talaga iyung pangyayari kahapon," Villar said in a phone interview with radio DZMM.

Dubbing the accident a "wake-up call," Villar said he has ordered a review of the country's railing standards and whether road barriers should be reinforced.

He said he is also looking into reports that the Carranglan railing was already damaged even before Tuesday's crash.

Reports said another bus reportedly hit the railing last July 12 in an accident that left 5 people dead and at least 20 others wounded.

Villar promised to draw a policy for the automatic repair of damaged road signs and railings.

He has also tasked infrastructure regional directors to identify accident-prone areas in road networks.

"Gagawin namin ang lahat para siguraduhin hindi na mauulit ang ganoong klaseng pangyayari," he vowed. (We will do everything to ensure that th is incident will not be repeated.)

Tuesday's accident has killed at least 31 people and injured 46 others, the Nueva Ecija police said.

The Land Transportation Franchising and Regulatory Board (LTFRB) is set to inspect the crash site on Wednesday morning.