Four of the ten national leaders of the Association of Southeast Asian Nations (ASEAN) missed the opening ceremony of the 15th ASEAN summit opened?in Hua Hin of Thailand?on Friday morning.

The absence of the national leaders of the Philippines, Cambodia, Indonesia and Malaysia also forced the canceling of a traditional group photo session at the ceremony at the Thai beach resort of Hua Hin. The four countries were represented by senior officials at the ceremony.

Indonesian President Susilo Bambang Yudhoyono is expected to miss Friday's summit meetings as he has to attend the inauguration for the second term of his presidency. He will arrive in Thailand in the evening.

ASEAN Secretary-General Surin Pitsuwan had said Cambodian Prime Minister Hun Sen had not been able to show up because he was busy meeting visiting South Korean President Lee Myung-bak, who was Hun Sen's former economic adviser. He will arrive in Hua Hin on Friday afternoon.

Malaysia's Prime Minister Najib Razak had to attend a parliament debate on budget proposals before departing for the summit in Thailand. He is expected to arrive in Thailand at about 9 p.m.

Philippine President Gloria Macapagal Arroyo is expected to arrive in Thailand on Friday night after Typhoon Ramil showed signs of weakening, her press secretary Cerge Remonde said in a news briefing in the Philippine capital of Manila.

The ASEAN summit is scheduled for Friday, followed by a series of related summits involving dialogue partners on Saturday and Sunday.

An official with Thailand's Ministry of Foreign Affairs had previously said that all the ten national leaders will attend the ASEAN Summit, "but a few of them will come late".