Thailand's candidate for the UN's top job will seek the support of the United States, China and its Southeast Asian neighbours at a regional meeting here this week, officials said Monday.

Deputy Prime Minister Surakiart Sathirathai is to meet with Association of Southeast Asian Nations (ASEAN) foreign ministers later Monday to boost his campaign in the face of growing competition from other countries in the region.

"We are entering the crucial period. A reaffirmation of support from ASEAN is very important," Sihasak Phuangketkeow, deputy permanent secretary at the Thai foreign ministry told AFP.

"We need to beef up our campaign," he said, adding that ASEAN is expected to lobby on behalf of Thailand.

Malaysia is also hosting Asia's top security forum, which convenes Thursday, giving Surakiart access to figures like US Secretary of State Condoleezza Rice and counterparts from China, India, Japan and South Korea.

The consensus at the United Nations is that it is now Asia's turn to have a secretary general. The winning candidate would replace Ghana's Kofi Annan, who will step down at the end of this year after having completed two five-year terms.

"Surakiart will use the opportunity to meet ASEAN's dialogue partners" to garner their support, Sihasak said when asked if Surakiart would appeal to the United States and regional power China for their backing.

Sihasak declined to rate Thailand's chances but said that "at least we are taken as a serious candidate".

"We are working hard on this. It is not an easy process," he said.

Indian candidate Shashi Tharoor, an undersecretary at the United Nations, has emerged as a favourite for the post.

Other top contenders include Sri Lankan presidential adviser Jayantha Dhanapala, South Korean Foreign Minister Ban Ki-Moon, and Latvian President Vike Frieberga.

Malaysian Foreign Minister Syed Hamid Albar defended his meeting Monday with Tharoor, who is in Kuala Lumpur for a conference organised by a local thinktank.

"There should not be any doubt, there should not be any question about ASEAN's support for the candidature of Dr. Surakiart," he told a press conference.

"In diplomacy we meet people all the time. The fact that they are adversaries or your opponents or they are contesting should not prevent us from meeting people."

"I met Shashi Tharoor just now, we had a discussion. He understood the ASEAN position. He said, I know, I'm not going to ask you for your support."