HANOI, Vietnam (CNN) -- The issue of Cambodia's admission into Southeast Asia's political organization sparked a diplomatic dispute on Tuesday.

Leading dignitaries attending the Association of Southeast Asian Nations summit seemed to have reached a compromise Monday night.

But the apparent agreement disintegrated the following day when diplomats offered conflicting views on when Cambodia could join -- or if it already had.

Cambodia was already a full member, said Vietnam Foreign Minister Nguyen Manh Cam at the end of the first day of the annual summit on Monday.

"The ASEAN leaders decided to admit Cambodia into ASEAN as the 10th member, so this is a very clear and definite decision... Right now Cambodia is a member," Cam said.

Yet Shanmugam Jayakumar, his Singaporean counterpart, said Phnom Penh would only join after fully carrying out constitutional reforms.

"We have decided (Cambodia's admission) will take place in Hanoi, but we have not decided on a date," Jayakumar said. "When they have implemented their coalition agreements they will be admitted."

Dispute downplayed

Indonesian President B.J. Habibie downplayed the dispute, saying on Tuesday the Cambodia question had not caused a rift within ASEAN. The association will likely delay the admission until after the Muslim fasting month of Ramadan in late January, he said.

ASEAN leaders issued a vague statement Monday saying Cambodia would join, but no definite date was given.

The announcement, however, said the admission would take place in Hanoi at a "special ceremony" arranged by ASEAN foreign ministers.

Singapore's Jayakumar, as the current head of ASEAN's standing committee, would coordinate the event.

"The political ceremony to admit Cambodia requires all (ASEAN) foreign ministers to sign...so until you get a consensus that's not going to happen," one senior ASEAN official said.

Former invitation withdrawn

ASEAN had agreed in 1995 to admit Cambodia, along with Laos and Myanmar, at a ceremony two years later. But when Cambodian Premier Hun Sen ousted his co-premier Prince Norodom Ranariddh in a July 1995 coup, the invitation was withdrawn.

The organization then required political stability as a precondition for another membership bid.

Hun Sen failed to attain a governing majority in elections that followed. Last month he was sworn in to head a coalition government that included his rival Ranariddh as National Assembly speaker.

Vietnam, Malaysia, Indonesia, Laos, Myanmar and Japan had lobbied for Cambodia's immediate ASEAN entry at the Hanoi summit.

Yet Singapore said Cambodia had to authorize through a constitutional amendment a new upper house or senate. Cambodia has pledged to take the action, but has not done so.

In Hanoi for an official visit and to attend the conference, Hun Sen said late on Monday the ASEAN leaders' decision had been a victory for the new Cambodian government. But after failing to secure immediate ASEAN entry, he has sat at the summit as an official visitor.

The Cambodian leader did receive some good news on Tuesday, although not from ASEAN. Japan's Prime Minister Keizo Obuchi, also attending the conference, promised continued financial assistance to Cambodia in a meeting with Hun Sen.

Japan, Cambodia's largest aid donor, will host an international meeting on assistance for Cambodia as early as February in Tokyo, Obuchi said.

ASEAN members are Brunei, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam.

Reuters contributed to this report.