WASHINGTON, May 14 (Reuters) - The head of the Association of Southeast Asian Nations said on Wednesday he understood growing frustration at the group's slow response to member Myanmar's cyclone but pleaded "don't just write us off yet."

Secretary-General Surin Pitsuwan said many outsiders were "very anxious, very angry and very frustrated, and you have the right to be."

The 10-member ASEAN has yet to mount a regional response, nearly two weeks after Cyclone Nargis struck the former Burma, which is ruled by a military government that has appealed for relief but refused to admit foreign aid workers.

"But ASEAN needs encouragement. ASEAN needs less of the criticism. ASEAN needs less of the ridicule," Surin, a former Thai foreign minister, told an audience at the Council on Foreign Relations in Washington.

He did not refer to specific criticism of the group.

"We are trying to work around a very, very strict resistance and mentality and mind-set that have been there for a long, long time," Surin said.

ASEAN ministers are due to meet on Monday in Singapore to discuss help for Myanmar, a crisis which Surin called "a defining moment for us."

The United Nations said on Wednesday up to 2.5 million people might have been affected by the high winds and wall of water that swept across Myanmar's Irrawaddy delta, where delays by the junta in admitting large-scale aid are threatening a massive humanitarian disaster.

The International Federation of the Red Cross estimated between 68,833 and 127,990 people had died.

The Harvard-educated Surin said he was often asked why ASEAN cannot "suspend" or "eject" Myanmar -- a country whose repression and economic mismanagement has often drawn criticism of the 40-year-old group and complicated ties with Europe and the United States.

"The same question may be asked about some members of the United Nations," he said. "It is not that simple." (Reporting by Paul Eckert; Editing by John O'Callaghan)

AlertNet news is provided by